Oil composition for use in trace oil supply cutting/grinding work

ABSTRACT

This invention provides an oil composition for cutting and grinding by minimum quantity lubrication system, characterized by comprising an ester oil with a kinematic viscosity of 0.5-20 mm 2 /s at 100° C., and an ester-based polymer with a kinematic viscosity exceeding 20 mm 2 /s at 100° C. and an average molecular weight of 5,000-10,000,000. The oil composition for cutting and grinding by minimum quantity lubrication system according to the invention can achieve an excellent balance between misting property and inhibition of floating mist and ensure that an adequate amount reaches the working section, for cutting and grinding by minimum quantity lubrication system.

TECHNICAL FIELD

The present invention relates to an oil composition for cutting andgrinding by minimum quantity lubrication (MQL) system, and morespecifically it relates to an oil composition for cutting and grindingof a workpiece while supplying a minimum quantity of oil to a workingsection together with a compressed fluid.

BACKGROUND ART

In cutting and grinding, it is common to employ cutting and grindingoils for the purpose of extending the life of working tools such asdrills, end mills, cutting tools, grinding wheels and the like,improving the surface roughness of working surfaces and raisingproductivity in mechanical working by increasing machining performance.

Cutting and grinding oils fall into two general categories, namelywater-soluble cutting and grinding oils used by diluting surfactants andlubricant components with water, and non-water-soluble cutting andgrinding oils used directly as stock solutions composed mainly ofmineral oils. In conventional cutting and grinding, a relatively largeamount of cutting and grinding oil is supplied to the working sectionregardless of the type of oil.

The most basic and important functions of a cutting and grinding oil arethe lubricating function and cooling function. Generally speakingnon-water-soluble cutting and grinding oils exhibit superior lubricatingperformance while water-soluble cutting and grinding oils exhibitsuperior cooling performance. Because the cooling effect ofnon-water-soluble oils is inferior to that of water-soluble oils, thereis usually required a large amount of non-water-soluble cutting andgrinding oil, from several liters to in some cases several tens ofliters per minute.

Cutting and grinding oils that are effective for improving machiningperformance have drawbacks from other viewpoints, typically theiradverse effects on the environment. Whether non-water-soluble orwater-soluble, oils undergo gradual degradation with use and eventuallybecome unusable. In the case of water-soluble oils, for example,solution stability is lost with growth of microorganisms, resulting inseparation of the components, significant fouling of the environment andunsuitability for use. In the case of non-water-soluble oils,progressive oxidation produces acidic components that corrode metalmaterials and produce significant changes in viscosity, also resultingin unsuitability for use. The oils also adhere to shaved chips and thelike, becoming consumed and forming waste.

The degraded oils must therefore be disposed of and replaced with newoils. Oils that have been discharged as waste must be treated in somemanner to avoid adversely affecting the environment. For example,chlorine-based compounds that can potentially generate harmful dioxinduring thermal disposal are often used in cutting and grinding oilsdeveloped for the principal purpose of improving working efficiency, andsuch compounds must therefore be removed. Cutting and grinding oilscontaining no chlorine-based compounds have therefore been developed,but even cutting and grinding oils free of such harmful componentsaffect the environment if their waste disposal volume is large.Water-soluble oils can also contaminate environmental waters andtherefore require costly high-level treatment.

Research has been conducted recently with cooling of cutting andgrinding areas by cool air blowing, instead of using cutting andgrinding oils, as a means of dealing with these problems, but thelubricating performance provided by cutting and grinding oils cannot beachieved.

In light of this background, a cutting and grinding process in minimumquantity lubrication system has been developed in which a trace amountof oil at about 1/100,000-1/1,000,000 of the amount of oil used forconventional cutting and grinding is supplied to the working sectiontogether with a compressed fluid (for example, compressed air) forcutting and grinding. In such systems, a cooling effect is achieved dueto the compressed air, and the trace amount of oil used allows theamount of waste to be reduced, thereby resulting in improvement in theeffect on the environment that is caused by large-scale emission ofwaste products (for example, see Patent documents 1, 2).

-   [Patent document 1] WO02/083823-   [Patent document 2] WO02/081605

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The oil used in the aforementioned minimum quantity lubrication systemcutting and grinding process must have the property of easily misting(hereinafter referred to as “misting property”), because of the mannerin which it is used. Using an oil with a low misting property results ininsufficient oil reaching the working section, making it impossible toensure adequate machining performance.

However, investigation by the present inventors has shown that simplyusing an oil with a high misting property produces a mist that floats inthe atmosphere as it forms and does not reach the working section, or amist that reaches the working section but flies away without remainingon the working section (hereinafter, this will be referred to as“floating mist”). This also reduces the effective amount of oilfunctioning at the working section, making it impossible to ensureadequate machining performance. Moreover, generation of a floating mistis also undesirable from the viewpoint of the working environment.

It is an object of the present invention, which has been accomplished inlight of the circumstances described above, to provide an oil that canachieve an excellent balance between the misting property and inhibitionof floating mist when performing cutting and grinding with minimumquantity lubrication system, thereby ensuring that a sufficient amountreaches the working section.

Means for Solving the Problems

In order to solve the problems described above, the oil composition forcutting and grinding by minimum quantity lubrication system according tothe invention is characterized by comprising an ester oil with akinematic viscosity of 0.5-20 mm²/s at 100° C. and an ester-basedpolymer with a kinematic viscosity exceeding 20 mm²/s at 100° C. and anaverage molecular weight of 5,000-10,000,000.

Ester-based polymers with a kinematic viscosity exceeding 20 mm²/s at100° C. include those with a measured kinematic viscosity of greaterthan at 100° C., as well as those whose kinematic viscosity at 100° C.is too high to be measured (semi-solids, solids and the like).

The oil composition for cutting and grinding by minimum quantitylubrication system according to the invention (hereinafter also referredto simply as “oil composition of the invention”) employs both an esteroil with a kinematic viscosity at 100° C. which satisfies theaforementioned conditions, and an ester-based polymer whose kinematicviscosity at 100° C. and average molecular weight satisfy theaforementioned conditions, thereby allowing an excellent balance to beachieved between the misting property and inhibition of floating mist,in order to ensure that an adequate amount reaches the working section.Moreover, upon reaching the working section, the oil composition of theinvention can adequately enhance the machining performance for cuttingand grinding with the minimum quantity lubrication system.

Although the reason for this effect of the invention is not fullyunderstood, the present inventors conjecture as follows. That is, it isbelieved that the high affinity of the ester-based polymer of theinvention for the ester oil provides a function of stably maintainingthe ester oil in the oil composition of the invention. Thus, while esteroils when used alone exhibit a very high misting property but formminute oil droplets that can result in floating mist, these are capturedby the ester-based polymer and prevented from forming a floating mist.On the other hand, ester oil droplets of a size that can separate fromthe ester-based polymer, as well as oil droplets composed of the esteroil and ester-based polymer, have a high misting property and areresistant to size increase by reaggregation, thus being able to reliablyreach the working section. The present inventors conjecture that theester oil droplet size-adjusting function of the ester-based polymer isresponsible for achieving both a misting property and inhibition offloating mist.

Effect of the Invention

The cutting and grinding oil for minimum quantity lubrication systemaccording to the invention can achieve an excellent balance betweenmisting property and inhibition of floating mist and ensure that anadequate amount reaches the working section, when cutting and grindingis carried out with minimum quantity lubrication system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the essential parts of the test apparatus usedin the examples.

FIG. 2 is a top view of the essential parts of the test apparatus usedin the examples.

EXPLANATION OF SYMBOLS

1: Table, 2: drill, 3: shank, 4: mist collector, 5: oil feed line, 10:workpiece.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred modes of the invention will now be described in detail.

The oil composition of the invention is an oil composition to be usedfor cutting and grinding with minimum quantity lubrication system, andit comprises (A) an ester oil with a kinematic viscosity of 0.5-20 mm²/sat 100° C. (hereinafter also referred to as “component (A)”), and (B) anester-based polymer with a kinematic viscosity of 20 mm²/s at 100° C.and an average molecular weight of 5,000-10,000,000 (hereinafter alsoreferred to as “component (B)”).

The term “cutting and grinding with minimum quantity lubrication system”used here refers to cutting and grinding which is carried out whilesupplying oil, in a trace amount of about 1/100,000-1/1,000,000 comparedto the amount of oil used for ordinary cutting and grinding, to acutting and grinding area, together with a compressed fluid (compressedair or the like). More specifically, minimum quantity lubrication systemis a system wherein oil is supplied at 0.001-1 ml/min toward the cuttingand grinding area together with a compressed fluid (for example,compressed air). A compressed fluid such as nitrogen, argon, helium,carbon dioxide or water may also be used alone in addition to compressedair, or such fluids may be used in combination.

The pressure of the compressed fluid for the cutting and grinding withminimum quantity lubrication system is adjusted to a pressure that doesnot cause fly-off of the oil and contamination of the ambient area, buta pressure that allows the oil and gas, or a fluid mixture thereof witha liquid, to sufficiently reach the cutting and grinding point. From thestandpoint of the cooling property, the temperature of the compressedfluid will usually be room temperature (about 25° C.), or will beadjusted to between room temperature and −50° C.

Component (A) used for the invention is not particularly restricted solong as it is an ester oil with a kinematic viscosity of 0.5-20 mm²/s at100° C., and the ester may be either a natural substance (usually onefound in a natural fat or oil from an animal or plant) or synthetic.According to the invention, synthetic esters are preferred from thestandpoint of stability of the resulting oil composition and uniformityof the ester component.

The alcohol in the ester oil used as component (A) may be a monohydricalcohol or polyhydric alcohol, and the acid in the ester oil may be amonobasic acid or polybasic acid.

As monohydric alcohols there may be used those with 1-24, preferably1-12, and more preferably 1-8 carbon atoms, and such alcohols may beeither straight-chain or branched, and either saturated or unsaturated.As specific examples of C1-24 alcohols there may be mentioned methanol,ethanol, straight-chain or branched propanol, straight-chain or branchedbutanol, straight-chain or branched pentanol, straight-chain or branchedhexanol, straight-chain or branched heptanol, straight-chain or branchedoctanol, straight-chain or branched nonanol, straight-chain or brancheddecanol, straight-chain or branched undecanol, straight-chain orbranched dodecanol, straight-chain or branched tridecanol,straight-chain or branched tetradecanol, straight-chain or branchedpentadecanol, straight-chain or branched hexadecanol, straight-chain orbranched heptadecanol, straight-chain or branched octadecanol,straight-chain or branched nonadecanol, straight-chain or branchedeicosanol, straight-chain or branched heneicosanol, straight-chain orbranched tricosanol, straight-chain or branched tetracosanol, andmixtures of these.

As polyhydric alcohols there may be used for most purposes 2-10 hydricalcohols, and preferably 2-6 hydric alcohols. As specific examples of2-10 hydric polyhydric alcohols there may be mentioned polyhydricalcohols including ethylene glycol, diethylene glycol and polyethyleneglycol (3-15mers of ethylene glycol), propylene glycol, dipropyleneglycol and polypropylene glycol (3-15mers of propylene glycol), dihydricalcohols such as 1,3-propanediol, 1,2-propanediol, 1,3-butanediol,1,4-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol,1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol andneopentyl glycol; glycerin, polyglycerin (2-8mers of glycerin, forexample, diglycerin, triglycerin, tetraglycerin, etc.),trimethylolalkanes (trimethylolethane, trimethylolpropane,trimethylolbutane, etc.) and their 2-8mers, pentaerythritols and their2-4mers, 1,2,4-butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol,1,2,3,4-butanetetrol, sorbitol, sorbitan, sorbitol-glycerin condensate,adonitol, arabitol, xylitol, mannitol and the like; and sugars such asxylose, arabinose, ribose, rhamnose, glucose, fructose, galactose,mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucroseand the like, as well as their mixtures.

Preferred among these polyhydric alcohols are 2-6 hydric polyhydricalcohols such as ethylene glycol, diethylene glycol, polyethylene glycol(3-10mers of ethylene glycol), propylene glycol, dipropylene glycol,polypropylene glycol (3-10mers of propylene glycol), 1,3-propanediol,2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol,glycerin, diglycerin, triglycerin, trimethylolalkanes(trimethylolethane, trimethylolpropane, trimethylolbutane, etc.) andtheir 2-4mers, pentaerythritol, dipentaerythritol, 1,2,4-butanetriol,1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol,sorbitan, sorbitol-glycerin condensate, adonitol, arabitol, xylitol,mannitol and the like, as well as mixtures thereof. More preferred areethylene glycol, propylene glycol, neopentyl glycol, glycerin,trimethylolethane, trimethylolpropane, pentaerythritol, sorbitan andmixtures thereof. Most preferred among these are neopentyl glycol,trimethylolethane, trimethylolpropane, pentaerythritol and mixturesthereof, since these can provide higher oxidation stability.

The alcohol of the ester oil used as component (A) may be a monohydricalcohol or polyhydric alcohol as mentioned above, but a polyhydricalcohol is preferred from the viewpoint of obtaining more excellentlubricity for cutting and grinding, improving the finished surfaceprecision of the workpiece and achieving a more notable anti-wear effectat the tool blade edge, promoting a low pour point and further improvingthe manageability during the winter season or in cold climates.

In most cases a C2-24 fatty acid will be used as a monobasic acid, amongacids for the ester oil used as component (A), and such fatty acids maybe straight-chain or branched and either saturated or unsaturated. Asspecific examples there may be mentioned saturated fatty acids such asacetic acid, propionic acid, straight-chain or branched butanoic acid,straight-chain or branched pentanoic acid, straight-chain or branchedhexanoic acid, straight-chain or branched heptanoic acid, straight-chainor branched octanoic acid, straight-chain or branched nonanoic acid,straight-chain or branched decanoic acid, straight-chain or branchedundecenoic acid, straight-chain or branched dodecanoic acid,straight-chain or branched tridecanoic acid, straight-chain or branchedtetradecanoic acid, straight-chain or branched pentadecanoic acid,straight-chain or branched hexadecanoic acid, straight-chain or branchedheptadecanoic acid, straight-chain or branched octadecanoic acid,straight-chain or branched hydroxyoctadecanoic acid, straight-chain orbranched nonadecanoic acid, straight-chain or branched eicosanoic acid,straight-chain or branched heneicosanoic acid, straight-chain orbranched docosanoic acid, straight-chain or branched tricosanoic acidand straight-chain or branched tetracosanoic acid; and unsaturated fattyacids such as acrylic acid, straight-chain or branched butenoic acid,straight-chain or branched pentenoic acid, straight-chain or branchedhexenoic acid, straight-chain or branched heptenoic acid, straight-chainor branched octenoic acid, straight-chain or branched nonenoic acid,straight-chain or branched decenoic acid, straight-chain or branchedundecenoic acid, straight-chain or branched dodecenoic acid,straight-chain or branched tridecenoic acid, straight-chain or branchedtetradecenoic acid, straight-chain or branched pentadecenoic acid,straight-chain or branched hexadecenoic acid, straight-chain or branchedheptadecenoic acid, straight-chain or branched octadecenoic acid,straight-chain or branched hydroxyoctadecenoic acid, straight-chain orbranched nonadecenoic acid, straight-chain or branched eicosenoic acid,straight-chain or branched heneicosenoic acid, straight-chain orbranched docosenoic acid, straight-chain or branched tricosenoic acidand straight-chain or branched tetracosenoic acid, as well as mixturesthereof. Among these, from the viewpoint of obtaining more excellentlubricity for cutting and grinding, improving precision of the finishingsurface of the workpiece and achieving an even greater anti-wear effectfor the tool blade edge, particularly C3-20 saturated fatty acids, C3-22unsaturated fatty acids and mixtures thereof are preferred, C4-18saturated fatty acids, C4-18 unsaturated fatty acids and their mixturesare more preferred and C4-18 unsaturated fatty acids are even morepreferred, while from the viewpoint of preventing sticking, C4-18saturated fatty acids are especially preferred.

As polybasic acids there may be mentioned C2-16 dibasic acids,trimellitic acid and the like. Such C2-16 dibasic acids may bestraight-chain or branched, and either saturated or unsaturated. Asspecific examples there may be mentioned ethanedioic acid, propanedioicacid, straight-chain or branched butanedioic acid, straight-chain orbranched pentanedioic acid, straight-chain or branched hexanedioic acid,straight-chain or branched heptanedioic acid, straight-chain or branchedoctanedioic acid, straight-chain or branched nonanedioic acid,straight-chain or branched decanedioic acid, straight-chain or branchedundecanedioic acid, straight-chain or branched dodecanedioic acid,straight-chain or branched tridecanedioic acid, straight-chain orbranched tetradecanedioic acid, straight-chain or branchedheptadecanedioic acid, straight-chain or branched hexadecanedioic acid,straight-chain or branched hexenedioic acid, straight-chain or branchedheptenedioic acid, straight-chain or branched octenedioic acid,straight-chain or branched nonenedioic acid, straight-chain or brancheddecenedioic acid, straight-chain or branched undecenedioic acid,straight-chain or branched dodecenedioic acid, straight-chain orbranched tridecenedioic acid, straight-chain or branchedtetradecenedioic acid, straight-chain or branched heptadecenedioic acid,straight-chain or branched hexadecenedioic acid, and mixtures thereof.

The acid of the ester oil used as component (A) may be a monobasic acidor polybasic acid as mentioned above, but it is preferred to use amonobasic acid to more easily obtain an ester contributing to animproved viscosity index and enhanced misting and anti-stickingproperties.

The combination of the alcohol and acid in the ester oil used ascomponent (A) may be any from among the following, for example, so longas the kinematic viscosity of the ester oil is 0.5-20 mm²/s at 100° C.

(i) Esters of monohydric alcohols and monobasic acids(ii) Esters of polyhydric alcohols and monobasic acids(iii) Esters of monohydric alcohols and polybasic acids(iv) Esters of polyhydric alcohols and polybasic acids(v) Mixed esters of monohydric alcohol and polyhydric alcohol mixturesand polybasic acids(vi) Mixed esters of polyhydric alcohols and monobasic acid andpolybasic acid mixtures(vii) Mixed esters of monohydric alcohol and polyhydric alcohol mixturesand monobasic acid and polybasic acid mixtures

Preferred among these are (ii) esters of polyhydric alcohols andmonobasic acids, from the standpoint of obtaining more excellentlubricity during cutting and grinding, improving the finished surfaceprecision of the workpiece and achieving a more notable anti-wear effectat the tool blade edge, promoting a low pour point, further improvingthe manageability during the winter season or in cold climates, moreeasily achieving a high viscosity index and further improving themisting property.

As naturally-derived esters to be used as component (A) there may bementioned natural fats and oils including vegetable oils such as palmoil, palm kernel oil, rapeseed oil, soybean oil, sunflower oil, andhigh-oleic rapeseed oil or high-oleic sunflower oil with increased oleicacid content among the glyceride fatty acids achieved by cross-breedingor gene recombination, as well as animal oils such as lard.

According to the invention, the ester oil obtained using a polyhydricalcohol as the alcohol component may be a complete ester obtained byesterification of all of the hydroxyl groups in the polyhydric alcohol,or a partial ester wherein some of the hydroxyl groups remain ashydroxyl groups without esterification. Likewise, an organic acid esterobtained using a polybasic acid as the acid component may be a completeester obtained by esterification of all of the carboxyl groups in thepolybasic acid, or it may be a partial ester wherein some of thecarboxyl groups remain as carboxyl groups without esterification. Fromthe standpoint of low-temperature manageability and misting property,component (A) is preferably a complete ester.

As mentioned above, the kinematic viscosity of component (A) at 100° C.is no greater than 20 mm²/s, preferably no greater than 17 mm²/s, morepreferably no greater than 15 mm²/s and even more preferably no greaterthan 12 mm²/s. If the kinematic viscosity of component (A) at 100° C.exceeds 20 mm²/s, the misting property will be inadequate and it will bedifficult to ensure that a sufficient amount of mist reaches the workingsection. Also as mentioned above, the kinematic viscosity of component(A) at 100° C. is preferably at least 0.5 mm²/s, more preferably atleast 0.7 mm²/s and even more preferably at least 0.9 mm²/s. If thekinematic viscosity of the ester oil at 100° C. is less than 0.5 mm²/s,it will not be possible to prevent generation of floating mist even byusing component (B), and the lubricity at the working section will beinadequate.

The molecular weight of component (A) is not particularly restricted solong as the kinematic viscosity at 100° C. is 0.5-20 mm²/s, but it ispreferably less than 5,000, more preferably no greater than 3,000 andeven more preferably no greater than 2,000. If the molecular weight ofcomponent (A) exceeds this upper limit, the misting property will tendto be reduced. The molecular weight of component (A) is also preferablyat least 100, more preferably at least 150 and even more preferably atleast 200. If the molecular weight of component (A) is below this lowerlimit, it will tend to be difficult to prevent generation of floatingmist even by using component (B). When component (A) contains two ormore ester oils with different molecular weights, the “molecular weightof component (A)” is the average molecular weight of the ester oils.

There are no particular restrictions on the pour point and viscosityindex of component (A), but the pour point is preferably no higher than−10° C. and more preferably no higher than −20° C. The viscosity indexis preferably between 100 and 200.

The iodine value of component (A) is preferably 0-80, more preferably0-60, even more preferably 0-40, yet more preferably 0-20 and mostpreferably 0-10. The bromine value of the ester of the invention ispreferably 0-50 gBr₂/100 g, more preferably 0-30 gBr₂/100 g, even morepreferably 0-20 gBr₂/100 g and most preferably 0-10 gBr₂/100 g. If theiodine value and bromine value of component (A) are within therespective ranges specified above, the resulting oil composition willtend to have further increased resistance to stickiness. The iodinevalue referred to here is the value measured by the indicator titrationmethod described in “Test methods for acid value, saponification value,ester value, iodine value, hydroxyl value and unsaponifiable matter ofchemical products” of JIS K 0070. The bromine value is the valuemeasured according to “Petroleum distillates and commercial aliphaticolefins—Determination of bromine number—Electric method” of JIS K 2605.

In order to impart more satisfactory lubricating performance to the oilcomposition of the invention, the hydroxyl value of component (A) ispreferably 0.01-300 mgKOH/g and the saponification value is preferably100-500 mgKOH/g. To provide even higher lubricity, the upper limit forthe hydroxyl value of component (A) according to the invention is morepreferably 200 mgKOH/g and most preferably 150 mgKOH/g, while the lowerlimit is more preferably 0.1 mgKOH/g, even more preferably 0.5 mgKOH/g,yet more preferably 1 mgKOH/g, even yet more preferably 3 mgKOH/g andmost preferably 5 mgKOH/g. The upper limit for the saponification valueof component (A) is more preferably 400 mgKOH/g, and the lower limit ismore preferably 200 mgKOH/g. The hydroxyl value referred to here is thevalue measured by the indicator titration method described in “Testmethods for acid value, saponification value, ester value, iodine value,hydroxyl value and unsaponifiable matter of chemical products” of JIS K0070. The saponification value is the value measured by the indicatortitration method described in “Testing method of lubricating oil foraircraft” of JIS K 2503.

Component (B) according to the invention is an ester-based polymer witha kinematic viscosity of greater than 20 mm²/s at 100° C. and an averagemolecular weight of 5,000-10,000,000. The term “ester-based polymer”according to the invention includes both (B-1) polymers having an esterbond in the main chain, and (B-2) polymers having an ester bond in aside chain.

The (B-1) polymers having an ester bond in the main chain are“polyesters”, i.e. polymers containing a polybasic acid and polyhydricalcohol as essential monomer components. Such polymers may bestraight-chain polyesters composed of dibasic acids and dihydricalcohols, or they may be complex esters composed of dibasic or greaterpolybasic acids and dihydric or greater polyhydric alcohols, andcontaining a tribasic or greater polybasic acid and/or a trihydric orgreater polyhydric alcohol as an essential monomer component. Either astraight-chain polyester or complex polyester may further include amonobasic acid and/or a monohydric alcohol. The polybasic acid andpolyhydric alcohol as essential monomer components and the monobasicacid and monohydric alcohol as optional monomer components may be any ofthe polybasic acids, polyhydric alcohols, monobasic acids and monohydricalcohols mentioned in explaining the component (A) above, andappropriate selection of the types and proportions of these constituentmonomers can yield an ester-based polymer as component (B).

The (B-2) polymers having an ester bond in a side chain may be obtained,for example, using a polymerizable monomer with an ethylenic unsaturatedbond and an ester bond. As such polymerizable monomers there arepreferably used monomers represented by the following general formula(B-2-1), (B-2-2) or (B-2-3).

[wherein R¹ and R² may be the same or different and each representshydrogen or C1-4 alkyl, R³ represents C1-18 alkylene, R⁴ represents aC1-24 hydrocarbon group and p represents 0 or 1.]

[wherein R¹ and R² may be the same or different and each representshydrogen or C1-4 alkyl, R³ represents C1-18 alkylene, R⁴ represents aC1-24 hydrocarbon group and p represents 0 or 1.]

[wherein R¹ and R² may be the same or different and each representshydrogen or C1-4 alkyl, R³ and R⁵ may be the same or different and eachrepresents C1-18 alkylene, R⁴ and R⁶ may be the same or different andeach represents a C1-24 hydrocarbon group, and p and q may be the sameor different and each represents 0 or 1.]

R¹ and R² in general formulas (B-2-1)-(B-2-3) above represent hydrogenor C1-4 alkyl. As C1-4 alkyl groups represented by R¹ and R² there maybe mentioned methyl, ethyl, straight-chain or branched propyl andstraight-chain or branched butyl. Preferred as R¹ and R² are hydrogen,methyl or ethyl, with hydrogen or methyl being more preferred. For thecompounds represented by general formulas (B-2-1) and (B-2-3), both R¹and R² are most preferably hydrogen. For the monomer represented bygeneral formula (B-2-2), most preferably R¹ is hydrogen and R² ismethyl.

As C1-18 alkylene groups represented by R³ and R⁵ there may be mentionedspecifically, methylene, ethylene, straight-chain or branched propylene,straight-chain or branched butylene, straight-chain or branched pentyl,straight-chain or branched hexylene, straight-chain or branchedheptylene, straight-chain or branched octylene, straight-chain orbranched nonylene, straight-chain or branched decylene, straight-chainor branched undecylene, straight-chain or branched dodecylene,straight-chain or branched tridecylene, straight-chain or branchedtetradecylene, straight-chain or branched pentadecylene, straight-chainor branched hexadecylene, straight-chain or branched heptadecylene andstraight-chain or branched octadecylene.

Also, p in general formulas (B-2-1)-(B-2-3) and p and q in generalformula (B-2-3) are each 0 or 1. When p and q are 0, the structure has adouble bonded carbon atom and an ester group carbon atom directly bondedtogether.

In the monomers represented by general formulas (B-2-1)-(B-2-3),preferably p and q are 0 or p and q are 1 and R³ and R⁵ are C1-10alkylene groups, more preferably p and q are 0 or p and q are 1 and R³and R⁵ are C1-4 alkylene groups, even more preferably p and q are 0 or pand q are 1 and R³ and R⁵ are methylene or ethylene, even yet morepreferably p and q are 0 or p and q are 1 and R³ and R⁵ are methylene,and most preferably p and q are 0.

As specific examples of C1-24 hydrocarbon groups represented by R⁴ andR⁶ there may be mentioned alkyl, cycloalkyl, alkenyl, alkylcycloalkyl,aryl, alkylaryl and arylalkyl.

As examples of alkyl groups there may be mentioned alkyl groups such asmethyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl,decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,heptadecyl and octadecyl (where the alkyl groups may be straight-chainor branched).

As examples of cycloalkyl groups there may be mentioned C5-7 cycloalkylgroups such as cyclopentyl, cyclohexyl and cycloheptyl. As examples ofthe aforementioned alkylcycloalkyl groups there may be mentioned C6-11alkylcycloalkyl groups such as methylcyclopentyl, dimethylcyclopentyl,methylethylcyclopentyl, diethylcyclopentyl, methylcyclohexyl,dimethylcyclohexyl, methylethylcyclohexyl, diethylcyclohexyl,methylcycloheptyl, dimethylcycloheptyl, methylethylcycloheptyl anddiethylcycloheptyl (with any positions of substitution of the alkylgroups on the cycloalkyl groups).

As examples of the aforementioned alkenyl groups there may be mentionedalkenyl groups such as butenyl, pentenyl, hexenyl, heptenyl, octenyl,nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl,pentadecenyl, hexadecenyl, heptadecenyl and octadecenyl (where thealkenyl groups may be straight-chain or branched, and the double bondsmay be at any positions).

As examples of the aforementioned aryl groups there may be mentionedaryl groups such as phenyl and naphthyl. As examples of theaforementioned alkylaryl groups there may be mentioned C7-18 alkylarylgroups such as tolyl, xylyl, ethylphenyl, propylphenyl, butylphenyl,pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, nonylphenyl,decylphenyl, undecylphenyl and dodecylphenyl (where the alkyl groups maybe straight-chain or branched and substituted at any positions on thearyl groups).

As examples of the aforementioned arylalkyl groups there may bementioned C7-12 arylalkyl groups such as benzyl, phenylethyl,phenylpropyl, phenylbutyl, phenylpentyl and phenylhexyl (where the alkylgroups may be straight-chain or branched).

The hydrocarbon groups represented by R⁴ and R⁶ are preferably C1-22hydrocarbon groups, more preferably C1-20 hydrocarbon groups and evenmore preferably C1-18 hydrocarbon groups.

The monomer represented by general formula (B-2-1) above is preferablyan ester of a monobasic fatty acid and a vinyl alcohol, wherein R⁴ is aC1-22 (preferably C1-20, and more preferably C1-18) hydrocarbon group.

The monomer represented by general formula (B-2-2) above is preferablyan acrylic acid ester wherein R⁴ is a C1-22 (preferably C1-20, and morepreferably C1-18) hydrocarbon group or a methacrylic acid ester whereinR⁴ is a C1-22 (preferably C1-20, and more preferably C1-18) hydrocarbongroup, and more preferably it is a methacrylic acid ester wherein R⁴ isa C1-22 (preferably C1-20, and more preferably C1-18) hydrocarbon group.

The monomer represented by general formula (B-2-3) is preferably amaleic acid diester or fumaric acid diester wherein R⁴ and R⁶ are bothC1-22 (preferably C1-20, and more preferably C1-18) hydrocarbon groups,and more preferably it is dimethyl maleate, diethyl maleate, dipropylmaleate, dibutyl maleate or the like.

Of the monomers represented by general formulas (B-2-1)-(B-2-3) above,monomers represented by general formula (B-2-2) are preferred from thestandpoint of stability and floating mist inhibition.

Component (B) may be a homopolymer consisting of a single type ofmonomer represented by general formulas (B-2-1)-(B-2-3) above, or it maybe a copolymer consisting of two or more thereof. In addition to themonomers represented by general formulas (B-2-1)-(B-2-3) above, theremay be further included monomers represented by the following generalformulas (B-2-4)-(B-2-7).

[wherein R¹ and R² may be the same or different and each representshydrogen or C1-4 alkyl, and R⁷ represents hydrogen or a C1-24hydrocarbon group.]

[wherein R¹ and R² may be the same or different and each representshydrogen or C1-4 alkyl, and X¹ and X² may be the same or different andeach represents hydrogen or C1-18 monoalkylamino.]

[wherein R¹ and R² may be the same or different and each representshydrogen or C1-4 alkyl, R⁸ represents C2-18 alkylene, r represents 0 or1 and X³ represents a C1-30 organic group containing a nitrogen atom.]

[wherein R¹ and R² may be the same or different and each representshydrogen or C1-4 alkyl, and X³ represents a C1-30 organic groupcontaining a nitrogen atom.]

R¹ and R² in general formulas (B-2-4)-(B-2-7) each represent hydrogen orC1-4 alkyl. When R¹ and R² are C1-4 alkyl groups, the alkyl groups maybe any of the C1-4 alkyl groups mentioned in explaining R¹ and R² for(B-2-1)-(B-2-3) above.

Also, R⁷ in general formula (B-2-4) is hydrogen or a C1-24 hydrocarbongroup. When R⁷ is a C1-24 hydrocarbon group, the hydrocarbon group maybe any of the C1-24 hydrocarbon groups mentioned in explaining R⁴ and R⁶above. R⁷ is preferably hydrogen or a C1-20 hydrocarbon group, morepreferably hydrogen or a C1-15 hydrocarbon group, even more preferablyhydrogen or a C1-10 hydrocarbon group and most preferably hydrogen or aC1-6 hydrocarbon group.

Also, X¹ and X² in general formula (B-2-5) each represent hydrogen orC1-18 monoalkylamino. The C1-18 monoalkylamino groups represented by X¹and X² are residues resulting from removal of hydrogen from the aminogroup of a C1-18 monoalkylamine group (—NHR⁸; where R⁸ is C1-18 alkyl).As C1-18 alkyl groups represented by R⁸ there may be mentioned alkylgroups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl,hexadecyl, heptadecyl and octadecyl (where the alkyl groups may bestraight-chain or branched).

As C2-18 alkylene groups represented by R⁸ in general formula (B-2-6)there may be mentioned, specifically, alkylene groups such as ethylene,propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene,decylene, undecylene, dodecylene, tridecylene, tetradecylene,pentadecylene, hexadecylene, heptadecylene and octadecylene (where thealkylene groups may be straight-chain or branched).

Also in (B-2-6), r represents 0 or 1. When r is 0, the structurecontains O (an oxygen atom) directly bonded to X³.

X³ in general formulas (B-2-6) and (B-2-7) is a C1-30 organic groupcontaining a nitrogen atom. The number of nitrogen atoms in the organicgroup represented by X³ is not particularly restricted but is preferablyone. As mentioned above, the number of carbon atoms in the organic grouprepresented by X³ is 1-30, preferably 1-20, and more preferably 1-16.

The organic group represented by X³ is preferably a group containing anoxygen atom, and it also preferably contains a ring. Particularly fromthe viewpoint of stability and machining performance, the organic grouprepresented by X³ preferably has an oxygen-containing ring. When theorganic group represented by X³ is a group containing a ring, the ringmay be an aliphatic ring or aromatic ring, but it is preferably analiphatic ring. The ring of the organic group represented by X³ ispreferably a 6-membered ring from the standpoint of stability andmachining performance.

As organic groups represented by X³ there may be mentioned,specifically, dimethylamino, diethylamino, dipropylamino, dibutylamino,anilino, toluidino, xylidino, acetylamino, benzoylamino, morpholino,pyrolyl, pyrrolino, pyridyl, methylpyridyl, pyrrolidinyl, piperidinyl,quinonyl, pyrrolidonyl, pyrrolidono, imidazolino and pyrazino, amongwhich morpholino is particularly preferred.

As preferred examples of monomers represented by general formula (B-2-4)there may be mentioned ethylene, propylene, 1-butene, 2-butene,isobutene and styrene.

As preferred examples of monomers represented by general formula (B-2-5)there may be mentioned maleic acid, fumaric acid, maleic acid amide,fumaric acid amide and mixtures thereof.

As preferred examples of monomers represented by general formula (B-2-6)or (B-2-7) there may be mentioned dimethylaminomethyl methacrylate,diethylaminomethyl methacrylate, dimethylaminoethyl methacrylate,diethylaminoethyl methacrylate, 2-methyl-5-vinylpyridine,morpholinomethyl methacrylate, morpholinoethyl methacrylate,N-vinylpyrrolidone and mixtures thereof.

Preferred among the monomers represented by general formulas(B-2-4)-(B-2-7) from the standpoint of stability and machiningperformance are monomers represented by general formulas (B-2-4),(B-2-6) and (B-2-7). Monomers represented by general formulas (B-2-6)and (B-2-7) are more preferred, especially for combination with monomersrepresented by general formula (B-2-2). Monomers represented by generalformulas (B-2-4) are more preferred for combination with monomersrepresented by general formula (B-2-3).

When component (B) of the invention is a copolymer comprising a monomerrepresented by general formulas (B-2-1)-(B-2-3) above or two or moremonomers represented by general formulas (B-2-4)-(B-2-7) above, thereare no particular restrictions on the polymerization form and it may bea block copolymer or random copolymer, although random copolymers arepreferred from the standpoint of stability and machining performance.

As preferred examples of (B-2) polymers having an ester bond in a sidechain there may be mentioned, specifically, polymethacrylates,polyacrylates, polyvinyl esters, isobutylene-fumaric acid diestercopolymers, styrene-fumaric acid diester copolymers and vinylacetate-fumaric acid diester copolymers.

An ester-based polymer as component (B) is one having a kinematicviscosity of greater than 20 mm²/s at 100° C. Ester-based polymers witha kinematic viscosity of up to 20 mm²/s at 100° C. are within thedefinition of component (A) according to the invention, and if such anester-based polymer is used instead of component (B), it will not bepossible to achieve both a misting property and inhibition of floatingmist.

The average molecular weight of component (B) must be at least 5,000 asmentioned above, and it is preferably at least 7,000 and more preferablyat least 10,000. If the average molecular weight of the ester-basedpolymer is less than 5,000, inhibition of floating mist will beinsufficient. The average molecular weight of component (B) must also beno greater than 10,000,000 as mentioned above, and it is preferably nogreater than 1,000,000, more preferably no greater than 500,000, evenmore preferably no greater than 300,000 and most preferably no greaterthan 150,000. If the average molecular weight of the ester-based polymeris greater than 10,000,000 the misting property will be insufficient.

There are no particular restrictions on the content of component (B),but it is preferably at least 0.001% by mass, more preferably at least0.005% by mass and even more preferably at least 0.01% by mass based onthe total weight of the composition. If the content of component (B) isless than 0.001% by mass, the inhibiting effect against floating mist byusing component (B) may not be adequately exhibited. The content ofcomponent (B) is also preferably no greater than 20% by mass, morepreferably no greater than 10% by mass and even more preferably nogreater than 8% by mass based on the total weight of the composition. Ifthe content of component (B) exceeds 20% by mass, the misting propertyand biodegradability will tend to be reduced.

The oil composition of the invention may consist entirely of components(A) and (B) described above, but if necessary it may further contain thefollowing base oils and additives.

As base oils in addition to components (A) and (B) there may bementioned mineral-based oils such as paraffin-based mineral oils andnaphthene-based mineral oils; polyolefins such as propylene oligomers,polybutene, polyisobutylene, C5-20 α-olefin oligomers and co-oligomersof ethylene and C5-20 α-olefins, or their hydrogenated forms;alkylbenzenes such as monoalkylbenzenes, dialkylbenzenes andpolyalkylbenzenes; alkylnaphthalenes such as monoalkylnaphthalenes,dialkylnaphthalenes and polyalkylnaphthalenes; polyglycols such aspolyethylene glycol, polypropylene glycol,polyoxyethylenepolyoxypropyleneglycol, polyethylene glycolmonoether,polypropyleneglycolmonoether,polyoxyethylenepolyoxypropyleneglycolmonoether, polyethyleneglycoldiether, polypropyleneglycol diether andpolyoxyethylenepolyoxypropyleneglycol diether; phenyl ethers such asmonoalkyldiphenyl ethers, dialkyldiphenyl ethers, monoalkyltriphenylethers, dialkyltriphenyl ethers, tetraphenyl ethers,monoalkyltetraphenyl ethers, dialkyltetraphenyl ethers and pentaphenylethers, silicone oils; fluoroethers such as perfluoroether, and thelike.

The content of such base oils is not particularly restricted so long asthey do not impair the performance of the oil composition of theinvention, but it is preferably no greater than 90% by mass, morepreferably no greater than 80% by mass, even more preferably no greaterthan 70% by mass, yet more preferably no greater than 50% by mass andeven yet more preferably no greater than 30% by mass, although mostpreferably no base oils are added in addition to components (A) and (B).

The oil composition of the invention preferably contains (C) an oilagent (preferably an oil agent with a molecular weight of less than5,000) from the viewpoint of further increasing the machining efficiencyand tool life.

As (C) oil agents there may be mentioned alcohol oil agents, carboxylicacid oil agents, unsaturated carboxylic acid sulfides, compoundsrepresented by the following general formula (C-1), compoundsrepresented by the following general formula (C-2), polyoxyalkylenecompounds, ester oil agents, polyhydric alcohol hydrocarbyl ethers,amine oil agents and the like.

[wherein R⁹ represents a C1-30 hydrocarbon group, a represents aninteger of 1-6 and b represents an integer of 0-5.]

[wherein R¹⁰ represents a C1-30 hydrocarbon group, C represents aninteger of 1-6 and D represents an integer of 0-5.]

An alcohol oil agent may be a monohydric alcohol or a polyhydricalcohol. From the standpoint of achieving even better machiningefficiency and tool life, C1-40 monohydric alcohols are preferred, C1-25alcohols are more preferred and C8-18 alcohols are most preferred.Specifically, there may be mentioned the examples of cited as alcoholsfor the base oil ester. These alcohols may be straight-chain or branchedand either saturated or unsaturated, but from the standpoint ofpreventing sticking, they are preferably saturated.

A carboxylic acid oil agent may be a monobasic acid or a polybasic acid.From the standpoint of achieving even higher machining efficiency andtool life, C1-40 monobasic carboxylic acids are preferred, C5-25carboxylic acids are more preferred and C5-20 carboxylic acids are mostpreferred. Specifically, there may be mentioned the examples ofcarboxylic acids cited for the base oil ester. These carboxylic acidsmay be straight-chain or branched and either saturated or unsaturated,but from the standpoint of preventing sticking, saturated carboxylicacids are preferred.

As examples of unsaturated carboxylic acid sulfides there may bementioned sulfides of unsaturated carboxylic acid oil agents among thosecited above. More specifically, there may be mentioned sulfides of oleicacid.

As examples of C1-30 hydrocarbon groups represented by R⁹ in compoundsrepresented by general formula (C-1) above, there may be mentioned C1-30straight-chain or branched alkyl, C5-7 cycloalkyl, C6-30alkylcycloalkyl, C2-30 straight-chain or branched alkenyl, C6-10 aryl,C7-30 alkylaryl and C7-30 arylalkyl. Among these, C1-30 straight-chainor branched alkyl groups are preferred, C1-20 straight-chain or branchedalkyl groups are more preferred, C1-10 straight-chain or branched alkylgroups are even more preferred, and C1-4 straight-chain or branchedalkyl groups are most preferred. As examples of C1-4 straight-chain orbranched alkyl groups there may be mentioned methyl, ethyl,straight-chain or branched propyl and straight-chain or branched butyl.

A hydroxyl group may be substituted at any position, but in the case oftwo or more hydroxyl groups they are preferably substituted at adjacentcarbon atoms. The symbol a is preferably an integer of 1-3 and morepreferably 2. The symbol b is preferably an integer of 0-3 and morepreferably 1 or 2. As an example of a compound represented by generalformula (1) there may be mentioned p-tert-butylcatechol.

As examples of C1-30 hydrocarbon groups represented by R¹⁰ in compoundsrepresented by general formula (C-2) above, there may be mentioned thesame ones as cited for the C1-30 hydrocarbon group represented by R⁹ ingeneral formula (C-1), and the preferred ones are also the same. Ahydroxyl group may be substituted at any position, but in the case oftwo or more hydroxyl groups they are preferably substituted at adjacentcarbon atoms. The symbol c is preferably an integer of 1-3 and morepreferably 2. The symbol d is preferably an integer of 0-3 and morepreferably 1 or 2. As examples of compounds represented by generalformula (2) there may be mentioned 2,2-dihydroxynaphthalene and2,3-dihydroxynaphthalene.

As examples of polyoxyalkylene compounds there may be mentionedcompounds represented by the following general formula (C-3) or (C-4).

R¹¹O—(R¹²O)_(e)—R¹³  (C-3)

[wherein R¹¹ and R¹³ may be the same or different and each representshydrogen or a C1-30 hydrocarbon group, R¹² represents C2-4 alkylene ande represents an integer such that the number-average molecular weight is100-3500.]

A-[(R¹⁴O)_(f)—R¹⁵]_(g)  (C-4)

[wherein A represents the residue of a polyhydric alcohol having 3-10hydroxyl groups of which all or a portion of the hydrogens of thehydroxyl groups have been removed, R¹⁴ represents C2-4 alkylene, R¹⁵represents hydrogen or a C1-30 hydrocarbon group, f represents aninteger such that the number-average molecular weight is 100-3500, and grepresents the same number as the number of hydrogens removed from thehydroxyl groups of A.]

In general formula (C-3), preferably either or both R¹¹ and R¹³ arehydrogen. As examples of C1-30 hydrocarbon groups represented by R¹¹ andR¹³ there may be mentioned the examples of C1-30 hydrocarbon groupsrepresented by R⁹ in general formula (C-1), and their preferred examplesare also the same. As specific examples of C2-4 alkylene groupsrepresented by R¹² there may be mentioned ethylene, propylene(methylethylene) and butylene (ethylethylene). The symbol e ispreferably a integer such that the number-average molecular weight is300-2000, and more preferably an integer such that the number-averagemolecular weight is 500-1500.

As specific examples of polyhydric alcohols having 3-10 hydroxyl groupsfor A in general formula (C-4) above, there may be mentioned polyhydricalcohols such as glycerin, polyglycerin (2-4mers of glycerin includingdiglycerin, triglycerin and tetraglycerin), trimethylolalkanes(trimethylolethane, trimethylolpropane, trimethylolbutane) and their2-4mers, pentaerythritol, dipentaerythritol, 1,2,4-butanetriol,1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol,sorbitan, sorbitol-glycerin condensate, adonitol, arabitol, xylitol,mannitol, iditol, tallitol, dulcitol, allitol and the like; and sugarssuch as xylose, arabinose, ribose, rhamnose, glucose, fructose,galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehaloseand sucrose. Preferred among these are glycerin, polyglycerin,trimethylolalkanes and their 2-4mers, pentaerythritol,dipentaerythritol, sorbitol and sorbitan.

As examples of C2-4 alkylene groups represented by R¹⁴ there may bementioned the same examples of C2-4 alkylene groups represented by R¹²in general formula (C-3). As examples of C1-30 hydrocarbon groupsrepresented by R¹⁵ there may be mentioned the same examples of C1-30hydrocarbon groups represented by R⁹ in general formula (C-1), and theirpreferred examples are also the same. At least one of the g R¹⁵ groupsis preferably hydrogen, and more preferably all of them are hydrogen.The symbol f is preferably an integer such that the number-averagemolecular weight is 300-2000, and more preferably an integer such thatthe number-average molecular weight is 500-1500.

The alcohol in an ester oil agent may be a monohydric alcohol orpolyhydric alcohol, and the carboxylic acid may be a monobasic acid orpolybasic acid.

Examples of monohydric alcohols and polyhydric alcohols in the ester oilinclude any monohydric alcohols and polyhydric alcohols, while the acidof the ester oil agent may be a monobasic acid or polybasic acid.

As monohydric alcohols there may be used those with 1-24, preferably1-12, and more preferably 1-8 carbon atoms, and such alcohols may beeither straight-chain or branched, and either saturated or unsaturated.As specific examples of C1-24 alcohols there may be mentioned methanol,ethanol, straight-chain or branched propanol, straight-chain or branchedbutanol, straight-chain or branched pentanol, straight-chain or branchedhexanol, straight-chain or branched heptanol, straight-chain or branchedoctanol, straight-chain or branched nonanol, straight-chain or brancheddecanol, straight-chain or branched undecanol, straight-chain orbranched dodecanol, straight-chain or branched tridecanol,straight-chain or branched tetradecanol, straight-chain or branchedpentadecanol, straight-chain or branched hexadecanol, straight-chain orbranched heptadecanol, straight-chain or branched octadecanol,straight-chain or branched nonadecanol, straight-chain or branchedeicosanol, straight-chain or branched heneicosanol, straight-chain orbranched tricosanol, straight-chain or branched tetracosanol, andmixtures of these.

As polyhydric alcohols there may usually be used 2-10 hydric alcohols,and preferably 2-6 hydric alcohols. As specific examples of 2-10 hydricpolyhydric alcohols there may be mentioned ethylene glycol, diethyleneglycol, polyethylene glycol (3-15mers of ethylene glycol), propyleneglycol, dipropylene glycol, polypropylene glycol (3-15mers of propyleneglycol), dihydric alcohols such as 1,3-propanediol, 1,2-propanediol,1,3-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol,2-methyl-1,3-propanediol, 1,2-pentanediol, 1,3-pentanediol,1,4-pentanediol, 1,5-pentanediol, neopentyl glycol and the like; otherpolyhydric alcohols such as glycerin, polyglycerin (2-8mers of glycerinincluding diglycerin, triglycerin and tetraglycerin), trimethylolalkanes(trimethylolethane, trimethylolpropane and trimethylolbutane) and their2-8mers, pentaerythritols and their 2-4mers, 1,2,4-butanetriol,1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol,sorbitan, sorbitol-glycerin condensate, adonitol, arabitol, xylitol,mannitol and the like; and sugars such as xylose, arabinose, ribose,rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose,maltose, isomaltose, trehalose and sucrose, and mixtures thereof.

Preferred among these polyhydric alcohols are 2-6 hydric polyhydricalcohols such as ethylene glycol, diethylene glycol, polyethylene glycol(3-10mers of ethylene glycol), propyleneglycol, dipropyleneglycol,polypropyleneglycol (3-10mers of propyleneglycol), 1,3-propanediol,2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol,glycerin, diglycerin, triglycerin, trimethylolalkanes(trimethylolethane, trimethylolpropane, trimethylolbutane, and the like)and their 2-4mers, pentaerythritol, dipentaerythritol,1,2,4-butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol,1,2,3,4-butanetetrol, sorbitol, sorbitan, sorbitol-glycerin condensate,adonitol, arabitol, xylitol, mannitol and the like, as well as mixturesthereof. More preferred are ethylene glycol, propylene glycol, neopentylglycol, glycerin, trimethylolethane, trimethylolpropane,pentaerythritol, sorbitan and mixtures thereof. Most preferred amongthese are neopentyl glycol, trimethylolethane, trimethylolpropane,pentaerythritol and mixtures thereof, since these can yield higher heatand oxidation stability.

The alcohol of the ester oil agent may be a monohydric alcohol orpolyhydric alcohol as mentioned above, but it is preferably a polyhydricalcohol from the standpoint of achieving machining efficiency and toollife, and of more easily lowering the pour point and further improvingmanageability in winter season and cold climates. Using a polyhydricalcohol ester will increase the effect of improving the finished surfaceprecision of the workpiece and preventing wear of the tool blade edgeduring cutting and grinding.

In most cases a C2-24 fatty acid will be used as the monobasic acidamong acids for the ester oil agent, and such fatty acids may bestraight-chain or branched and either saturated or unsaturated. Asspecific examples there may be mentioned saturated fatty acids such asacetic acid, propionic acid, straight-chain or branched butanoic acid,straight-chain or branched pentanoic acid, straight-chain or branchedhexanoic acid, straight-chain or branched heptanoic acid, straight-chainor branched octanoic acid, straight-chain or branched nonanoic acid,straight-chain or branched decanoic acid, straight-chain or branchedundecanoic acid, straight-chain or branched dodecanoic acid,straight-chain or branched tridecanoic acid, straight-chain or branchedtetradecanoic acid, straight-chain or branched pentadecanoic acid,straight-chain or branched hexadecanoic acid, straight-chain or branchedheptadecanoic acid, straight-chain or branched octadecanoic acid,straight-chain or branched hydroxyoctadecanoic acid, straight-chain orbranched nonadecanoic acid, straight-chain or branched eicosanoic acid,straight-chain or branched heneicosanoic acid, straight-chain orbranched docosanoic acid, straight-chain or branched tricosanoic acidand straight-chain or branched tetracosanoic acid; and unsaturated fattyacids such as acrylic acid, straight-chain or branched butenoic acid,straight-chain or branched pentanoic acid, straight-chain or branchedhexenoic acid, straight-chain or branched heptenoic acid, straight-chainor branched octenoic acid, straight-chain or branched nonenoic acid,straight-chain or branched decenoic acid, straight-chain or branchedundecenoic acid, straight-chain or branched dodecenoic acid,straight-chain or branched tridecenoic acid, straight-chain or branchedtetradecenoic acid, straight-chain or branched pentadecenoic acid,straight-chain or branched hexadecenoic acid, straight-chain or branchedheptadecenoic acid, straight-chain or branched octadecenoic acid,straight-chain or branched hydroxyoctadecenoic acid, straight-chain orbranched nonadecenoic acid, straight-chain or branched eicosenoic acid,straight-chain or branched heneicosenoic acid, straight-chain orbranched docosenoic acid, straight-chain or branched tricosenoic acidand straight-chain or branched tetracosenoic acid, as well as mixturesthereof. From the viewpoint of achieving superior working efficiency andtool life, as well as manageability, C3-20 saturated fatty acids, C3-22unsaturated fatty acids and their mixtures are preferred, C4-18saturated fatty acids, C4-18 unsaturated fatty acids and their mixturesare more preferred and C4-18 unsaturated fatty acids are even morepreferred, and from the viewpoint of sticking prevention, C4-18saturated fatty acids are preferred.

As polybasic acids there may be mentioned C2-16 dibasic acids,trimellitic acid and the like. Such C2-16 dibasic acids may bestraight-chain or branched, and either saturated or unsaturated. Asspecific examples there may be mentioned ethanedioic acid, propanedioicacid, straight-chain or branched butanedioic acid, straight-chain orbranched pentanedioic acid, straight-chain or branched hexanedioic acid,straight-chain or branched heptanedioic acid, straight-chain or branchedoctanedioic acid, straight-chain or branched nonanedioic acid,straight-chain or branched decanedioic acid, straight-chain or branchedundecenedioic acid, straight-chain or branched dodecanedioic acid,straight-chain or branched tridecanedioic acid, straight-chain orbranched tetradecanedioic acid, straight-chain or branchedheptadecanedioic acid, straight-chain or branched hexadecanedioic acid,straight-chain or branched hexenedioic acid, straight-chain or branchedheptenedioic acid, straight-chain or branched octenedioic acid,straight-chain or branched nonenedioic acid, straight-chain or brancheddecenedioic acid, straight-chain or branched undecenedioic acid,straight-chain or branched dodecenedioic acid, straight-chain orbranched tridecenedioic acid, straight-chain or branchedtetradecenedioic acid, straight-chain or branched heptadecenedioic acid,straight-chain or branched hexadecenedioic acid, and mixtures thereof.

The combination of alcohol and acid in the ester oil agent may be asdesired without any particular restrictions, but the following estersmay be mentioned as preferred examples for ester oil agents to be usedfor the invention.

(i) Esters of monohydric alcohols and monobasic acids(ii) Esters of polyhydric alcohols and monobasic acids(iii) Esters of monohydric alcohols and polybasic acids(iv) Esters of polyhydric alcohols and polybasic acids(v) Mixed esters of monohydric alcohol and polyhydric alcohol mixturesand polybasic acids(vi) Mixed esters of polyhydric alcohols and monobasic acid andpolybasic acid mixtures(vii) Mixed esters of monohydric alcohol and polyhydric alcohol mixturesand monobasic acid and polybasic acid mixtures

When a polyhydric alcohol is used as the alcohol component, the estermay be a complete ester obtained by esterification of all of thehydroxyl groups in the polyhydric alcohol, or a partial ester whereinsome of the hydroxyl groups remain as hydroxyl groups withoutesterification. When a polybasic acid is used as the carboxylic acidcomponent, the ester may be a complete ester obtained by esterificationof all of the carboxyl groups in the polybasic acid, or a partial esterwherein some of the carboxyl groups remain as carboxyl groups withoutesterification. From the standpoint of machining performance, the esteroil agent is preferably a partial ester.

There are no particular restrictions on the total number of carbon atomsin the ester oil agent, but from the standpoint of achieving superiormachining efficiency and tool life, the ester preferably has a total ofat least 7 carbon atoms, more preferably at least 9 carbon atoms andmost preferably at least 11 carbon atoms. From the standpoint ofavoiding increased staining and corrosion, and of compatibility withorganic materials, the ester preferably has a total of no greater than60 carbon atoms, more preferably no greater than 45 carbon atoms, evenmore preferably no greater than 26 carbon atoms, yet more preferably nogreater than 24 carbon atoms and most preferably no greater than 22carbon atoms.

The polyhydric alcohol in the polyhydric alcohol hydrocarbyl ether willusually be a 2-10 hydric and preferably 2-6 hydric compound. As specificexamples of 2-10 hydric polyhydric alcohols there may be mentionedethylene glycol, diethylene glycol, polyethylene glycol (3-15mers ofethylene glycol), propylene glycol, dipropylene glycol, polypropyleneglycol (3-15mers of propylene glycol), dihydric alcohols such as1,3-propanediol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol,2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, 1,2-pentanediol,1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, neopentyl glycol andthe like; polyhydric alcohols such as glycerin, polyglycerin (2-8mers ofglycerin including diglycerin, triglycerin and tetraglycerin),trimethylolalkanes (trimethylolethane, trimethylolpropane andtrimethylolbutane) and their 2-8mers, pentaerythritols and their2-4mers, 1,2,4-butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol,1,2,3,4-butanetetrol, sorbitol, sorbitan, sorbitol-glycerin condensate,adonitol, arabitol, xylitol, mannitol and the like; and sugars such asxylose, arabinose, ribose, rhamnose, glucose, fructose, galactose,mannose, sorbose, cellobiose, maltose, isomaltose, trehalose andsucrose, and mixtures thereof.

Preferred among these polyhydric alcohols are 2-6 hydric polyhydricalcohols such as ethylene glycol, diethylene glycol, polyethylene glycol(3-10mers of ethylene glycol), propyleneglycol, dipropyleneglycol,polypropyleneglycol (3-10mers of propyleneglycol), 1,3-propanediol,2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol,glycerin, diglycerin, triglycerin, trimethylolalkanes(trimethylolethane, trimethylolpropane, trimethylolbutane, and the like)and their 2-4mers pentaerythritol, dipentaerythritol, 1,2,4-butanetriol,1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol,sorbitan, sorbitol-glycerin condensate, adonitol, arabitol, xylitol,mannitol and the like, as well as mixtures thereof. More preferred areethylene glycol, propylene glycol, neopentyl glycol, glycerin,trimethylolethane, trimethylolpropane, pentaerythritol, sorbitan andmixtures thereof. Among these, glycerin is most preferred from thestandpoint of achieving superior machining efficiency and tool life.

The polyhydric alcohol hydrocarbyl ether used may be one having all oronly a portion of the hydroxyl groups of the polyhydric alcoholconverted by hydrocarbyl etherification. From the standpoint ofachieving superior machining efficiency and tool life, preferably only aportion of the hydroxyl groups of the polyhydric alcohol are convertedby hydrocarbyl etherification (partial etherified product). Thehydrocarbyl group referred to here is a C1-24 hydrocarbon group such asC1-24 alkyl, C2-24 alkenyl, C5-7 cycloalkyl, C6-11 alkylcycloalkyl,C6-10 aryl, C7-18 alkylaryl or C7-18 arylalkyl.

As C1-24 alkyl groups there may be mentioned methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, straight-chain orbranched pentyl, straight-chain or branched hexyl, straight-chain orbranched heptyl, straight-chain or branched octyl, straight-chain orbranched nonyl, straight-chain or branched decyl, straight-chain orbranched undecyl, straight-chain or branched dodecyl, straight-chain orbranched tridecyl, straight-chain or branched tetradecyl, straight-chainor branched pentadecyl, straight-chain or branched hexadecyl,straight-chain or branched heptadecyl, straight-chain or branchedoctadecyl, straight-chain or branched nonadecyl, straight-chain orbranched eicosyl, straight-chain or branched heneicosyl, straight-chainor branched docosyl, straight-chain or branched tricosyl andstraight-chain or branched tetracosyl.

As C2-24 alkenyl groups there may be mentioned vinyl, straight-chain orbranched propenyl, straight-chain or branched butenyl, straight-chain orbranched pentenyl, straight-chain or branched hexenyl, straight-chain orbranched heptenyl, straight-chain or branched octenyl, straight-chain orbranched nonenyl, straight-chain or branched decenyl, straight-chain orbranched undecenyl, straight-chain or branched dodecenyl, straight-chainor branched tridecenyl, straight-chain or branched tetradecenyl,straight-chain or branched pentadecenyl, straight-chain or branchedhexadecenyl, straight-chain or branched heptadecenyl, straight-chain orbranched octadecenyl, straight-chain or branched nonadecenyl,straight-chain or branched eicosenyl, straight-chain or branchedheneicosenyl, straight-chain or branched docosenyl, straight-chain orbranched tricosenyl and straight-chain or branched tetracosenyl.

As C5-7 cycloalkyl groups there may be mentioned cyclopentyl, cyclohexyland cycloheptyl. As C6-11 alkylcycloalkyl groups there may be mentionedmethylcyclopentyl, dimethylcyclopentyl (including all structuralisomers), methylethylcyclopentyl (including all structural isomers),diethylcyclopentyl (including all structural isomers), methylcyclohexyl,dimethylcyclohexyl (including all structural isomers),methylethylcyclohexyl (including all structural isomers),diethylcyclohexyl (including all structural isomers), methylcycloheptyl,dimethylcycloheptyl (including all structural isomers),methylethylcycloheptyl (including all structural isomers) anddiethylcycloheptyl (including all structural isomers).

As C6-10 aryl groups there may be mentioned phenyl and naphthyl. AsC7-18 alkylaryl groups there may be mentioned tolyl (including allstructural isomers), xylyl (including all structural isomers),ethylphenyl (including all structural isomers), straight-chain orbranched propylphenyl (including all structural isomers), straight-chainor branched butylphenyl (including all structural isomers),straight-chain or branched pentylphenyl (including all structuralisomers), straight-chain or branched hexylphenyl (including allstructural isomers), straight-chain or branched heptylphenyl (includingall structural isomers), straight-chain or branched octylphenyl(including all structural isomers), straight-chin or branchednonylphenyl (including all structural isomers), straight-chain orbranched decylphenyl (including all structural isomers), straight-chainor branched undecylphenyl (including all structural isomers) andstraight-chain or branched dodecylphenyl (including all structuralisomers).

As C7-12 arylalkyl groups there may be mentioned benzyl, phenylethyl,phenylpropyl (including propyl isomers), phenylbutyl (including butylisomers), phenylpentyl (including pentyl isomers) and phenylhexyl(including hexyl isomers).

Preferred among these from the standpoint of achieving superiormachining efficiency and tool life are C2-18 straight-chain or branchedalkyl groups and C2-18 straight-chain or branched alkenyl groups, amongwhich C3-12 straight-chain or branched alkyl and oleyl (residue obtainedby removing hydroxyl from oleyl alcohol) are more preferred.

A monoamine is preferred for use as an amine oil agent. The number ofcarbon atoms of the monoamine is preferably 6-24 and more preferably12-24. Here, the number of carbon atoms is the total number of carbonatoms of the monoamine, and when the monoamine has two or morehydrocarbon groups it is the total number of their carbon atoms.

Monoamines to be used for the invention include primary monoamines,secondary monoamines and tertiary monoamines, although primarymonoamines are preferred from the standpoint of increasing workingefficiency and extending tool life.

As hydrocarbon groups bonded to the nitrogen atom of the monoamine theremay be used alkyl, alkenyl, cycloalkyl, alkylcycloalkyl, aryl,alkylaryl, arylalkyl and the like, although alkyl and alkenyl groups arepreferred from the standpoint of achieving superior machining efficiencyand tool life. The alkyl and alkenyl groups may be straight-chain orbranched, but are preferably straight-chain from the standpoint ofachieving superior machining efficiency and tool life.

As specific examples of preferred monoamines to be used for theinvention there may be mentioned hexylamine (including all isomers),heptylamine (including all isomers), octylamine (including all isomers),nonylamine (including all isomers), decylamine (including all isomers),undecylamine (including all isomers), dodecylamine (including allisomers), tridecylamine (including all isomers), tetradecylamine(including all isomers), pentadecylamine (including all isomers),hexadecylamine (including all isomers), heptadecylamine (including allisomers), octadecylamine (including all isomers), nonadecylamine(including all isomers), eicosylamine (including all isomers),heneicosylamine (including all isomers), docosylamine (including allisomers), tricosylamine (including all isomers), tetracosylamine(including all isomers), octadecenylamine (including all isomers)(including oleylamine and the like), and mixtures of two or morethereof. Among these, C12-24 primary monoamines are preferred, C14-20primary monoamines are more preferred and C16-18 primary monoamines areeven more preferred, from the standpoint of achieving superior machiningefficiency and tool life.

According to the invention, only one selected from among theaforementioned oil agents may be used, or a mixture of two or morethereof may be used. Preferred among these, from the standpoint ofachieving superior machining efficiency and tool life, are one or amixture of two or more selected from carboxylic acid oil agents andamine oil agents.

The content of the (C) oil agent is not particularly restricted, butfrom the standpoint of achieving superior machining efficiency and toollife, it is preferably at least 0.01% by mass, more preferably at least0.05% by mass and even more preferably at least 0.1% by mass based onthe total weight of the composition. From the standpoint of stability,the oil agent content is preferably no greater than 15% by mass, morepreferably no greater than 10% by mass and even more preferably nogreater than 5% by mass based on the total weight of the composition.

The oil composition of the invention preferably also further contains(D) an extreme-pressure agent, from the viewpoint of achieving superiormachining efficiency and tool life. Particularly when the (D)extreme-pressure agent is used together with the (C) oil agent describedabove, the components work synergistically to allow even greatersuperiority to be achieved in machining efficiency and tool life. Asdescribed hereunder, the oil composition of the invention may be used asa lubricating oil for sections other than machine tool working sections,in which case they preferably contain the (C) oil agent.

As preferred extreme pressure agents there may be mentioned the sulfurcompounds and phosphorus compounds mentioned below.

There are no particular restrictions on sulfur compounds to be used solong as the properties of the oil composition of the invention are notimpaired, but preferred for use are dihydrocarbyl polysulfide,sulfidized esters, sulfide mineral oils, zinc dithiophosphate compounds,zinc dithiocarbaminate compounds, molybdenum dithiophosphate compoundsand molybdenum dithiocarbaminate.

Dihydrocarbyl polysulfides are sulfur-based compounds commonly known aspolysulfides or olefin sulfides, and specifically they are representedby the following general formula (D-1).

R¹⁶—S_(h)—R¹⁷  (D-1)

[wherein R¹⁶ and R¹⁷ may be the same or different and each representsC3-20 straight chain or branched alkyl, C6-20 aryl, C6-20 alkylaryl orC6-20 arylalkyl, and h represents an integer of 2-6 and preferably 2-5.]

As specific examples of R¹⁶ and R¹⁷ in general formula (D-1) there maybe mentioned straight chain or branched alkyl groups such as n-propyl,isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, straight-chain orbranched pentyl, straight-chain or branched hexyl, straight-chain orbranched heptyl, straight-chain or branched octyl, straight-chain orbranched nonyl, straight-chain or branched decyl, straight-chain orbranched undecyl, straight-chain or branched dodecyl, straight-chain orbranched tridecyl, straight-chain or branched tetradecyl, straight-chainor branched pentadecyl, straight-chain or branched hexadecyl,straight-chain or branched heptadecyl, straight-chain or branchedoctadecyl, straight-chain or branched nonadecyl and straight-chain orbranched eicosyl; aryl groups such as phenyl and naphthyl; alkylarylgroups such as tolyl (including all structural isomers), ethylphenyl(including all structural isomers), straight-chain or branchedpropylphenyl (including all structural isomers), straight-chain orbranched butylphenyl (including all structural isomers), straight-chainor branched pentylphenyl (including all structural isomers),straight-chain or branched hexylphenyl (including all structuralisomers), straight-chain or branched heptylphenyl (including allstructural isomers), straight-chain or branched octylphenyl (includingall structural isomers), straight-chain or branched nonylphenyl(including all structural isomers), straight-chain or brancheddecylphenyl (including all structural isomers), straight-chain orbranched undecylphenyl (including all structural isomers),straight-chain or branched dodecylphenyl (including all structuralisomers), xylyl (including all structural isomers), ethylmethylphenyl(including all structural isomers), diethylphenyl (including allstructural isomers), di(straight-chain or branched)propylphenyl(including all structural isomers), di(straight-chain orbranched)butylphenyl (including all structural isomers), methylnaphthyl(including all structural isomers), ethylnaphthyl (including allstructural isomers), straight-chain or branched propylnaphthyl(including all structural isomers), straight-chain or branchedbutylnaphthyl (including all structural isomers), dimethylnaphthyl(including all structural isomers), ethylmethylnaphthyl (including allstructural isomers), diethylnaphthyl (including all structural isomers),di(straight-chain or branched)propylnaphthyl (including all structuralisomers) and di(straight-chain or branched)butylnaphthyl (including allstructural isomers); and arylalkyl groups such as benzyl, phenylethyl(including all isomers) and phenylpropyl (including all isomers). Amongthese there are preferred compounds wherein R¹⁶ and R¹⁷ in generalformula (D-1) are C3-18 alkyl groups derived from propylene, 1-butene orisobutylene, or C6-8 aryl, alkylaryl or arylalkyl groups, and asexamples of such groups there may be mentioned alkyl groups such asisopropyl, branched hexyl derived from propylene dimer (including allbranched isomers), branched nonyl derived from propylene trimer(including all branched isomers), branched dodecyl derived frompropylene tetramer (including all branched isomers), branched pentadecylderived from propylene pentamer (including all branched isomers),branched octadecyl derived from propylene hexamer (including allbranched isomers), sec-butyl, tert-butyl, branched octyl derived from1-butene dimer (including all branched isomers), branched octyl derivedfrom isobutylene dimer (including all branched isomers), brancheddodecyl derived from 1-butene trimer (including all branched isomers),branched dodecyl derived from isobutylene trimer (including all branchedisomers), branched hexadecyl derived from 1-butene tetramer (includingall branched isomers) and branched hexadecyl derived from isobutylenetetramer (including all branched isomers); alkylaryl groups such asphenyl, tolyl (including all structural isomers), ethylphenyl (includingall structural isomers) and xylyl (including all structural isomers);and arylalkyl groups such as benzyl and phenylethyl (including allisomers).

From the standpoint of achieving superior machining efficiency and toollife, R¹⁶ and R¹⁷ in general formula (D-1) above are more preferablyeach separately a C3-18 branched alkyl group derived from ethylene orpropylene and most preferably a C6-15 branched alkyl group derived fromethylene or propylene.

As specific examples of sulfidized esters there may be mentioned thoseprepared by sulfidizing of vegetable oils and fats such as beef tallow,lard, fish oil, rapeseed oil and soybean oil; unsaturated fatty acidesters obtained by reacting unsaturated fatty acids (including oleicacid, linoleic acid and fatty acids extracted from the aforementionedanimal and vegetable oils and fats) and various alcohols; as well asmixtures thereof, by any desired methods.

A sulfide mineral oil is a mineral oil in which simple sulfur isdissolved. The mineral oil used for the sulfide mineral oil of theinvention is not particularly restricted, and specifically there may bementioned paraffin-based mineral oils, naphthene-based mineral oils andthe like obtained by refining lube-oil distillates, in turn obtained byatmospheric distillation and vacuum distillation of stock oil, by anappropriate combination of refining treatments such as solventdeasphalting, solvent extraction, hydrotreatment, solvent dewaxing,catalytic dewaxing, hydrorefining, sulfuric acid cleaning, white claytreatment or the like. The simple sulfur may be in the form of a mass,powder, molten liquid or the like, but simple sulfur in powder or moltenliquid form is preferred for use because it allows efficient dissolutionin base oils. Simple sulfur in molten liquid form is miscible with otherliquids and therefore has the advantage of allowing the solutionoperation to be accomplished in a very brief period, but the handlingtemperature must be above the melting point of simple sulfur, requiringspecial apparatuses such as heating equipment, and because it must behandled in a high temperature atmosphere the handling is oftenassociated with danger. Simple sulfur in powder form, however, isinexpensive and easy to handle and has a sufficiently short dissolutiontime, and is therefore particularly preferred. There are no particularrestrictions on the sulfur content of a sulfide mineral oil for theinvention, but in most cases it is preferably 0.05-1.0% by mass and morepreferably 0.1-0.5% by mass based on the total weight of the sulfidemineral oil.

The zinc dithiophosphate compounds, zinc dithiocarbaminate compounds,molybdenum dithiophosphate compounds and molybdenum dithiocarbaminatecompounds referred to here are compounds represented by the followinggeneral formulas (D-2)-(D-5).

[wherein R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸, R²⁹,R³⁰, R³¹, R³² and R³³ may be the same or different and each represents aC1 or greater hydrocarbon group, and Y¹ and Y² each represent an oxygenor sulfur atom.]

As specific examples of hydrocarbon groups represented by R¹⁸-R³³ theremay be mentioned alkyl groups such as methyl, ethyl, propyl (includingall branched isomers), butyl (including all branched isomers), pentyl(including all branched isomers), hexyl (including all branchedisomers), heptyl (including all branched isomers), octyl (including allbranched isomers), nonyl (including all branched isomers), decyl(including all branched isomers), undecyl (including all branchedisomers), dodecyl (including all branched isomers), tridecyl (includingall branched isomers), tetradecyl (including all branched isomers),pentadecyl (including all branched isomers), hexadecyl (including allbranched isomers), heptadecyl (including all branched isomers),octadecyl (including all branched isomers), nonadecyl (including allbranched isomers), eicosyl (including all branched isomers), heneicosyl(including all branched isomers), docosyl (including all branchedisomers), tricosyl (including all branched isomers) and tetracosyl(including all branched isomers); cycloalkyl groups such as cyclopentyl,cyclohexyl and cycloheptyl; alkylcycloalkyl groups such asmethylcyclopentyl (including all substituted isomers), ethylcyclopentyl(including all substituted isomers), dimethylcyclopentyl (including allsubstituted isomers), propylcyclopentyl (including all branched isomersand substituted isomers), methyl ethylcyclopentyl (including allsubstituted isomers), trimethylcyclopentyl (including all substitutedisomers), butylcyclopentyl (including all branched isomers andsubstituted isomers), methylpropylcyclopentyl (including all branchedisomers and substituted isomers), diethylcyclopentyl (including allsubstituted isomers), dimethyl ethylcyclopentyl (including allsubstituted isomers), methylcyclohexyl (including all substitutedisomers), ethylcyclohexyl (including all substituted isomers),dimethylcyclohexyl (including all substituted isomers), propylcyclohexyl(including all branched isomers and substituted isomers),methylethylcyclohexyl (including all substituted isomers),trimethylcyclohexyl (including all substituted isomers), butylcyclohexyl(including all branched isomers and substituted isomers),methylpropylcyclohexyl (including all branched isomers and substitutedisomers), diethylcyclohexyl (including all substituted isomers),dimethylethylcyclohexyl (including all substituted isomers),methylcycloheptyl (including all substituted isomers), ethylcycloheptyl(including all substituted isomers), dimethylcycloheptyl (including allsubstituted isomers), propylcycloheptyl (including all branched isomersand substituted isomers), methylethylcycloheptyl (including allsubstituted isomers), trimethylcycloheptyl (including all substitutedisomers), butylcycloheptyl (including all branched isomers andsubstituted isomers), methylpropylcycloheptyl (including all branchedisomers and substituted isomers), diethylcycloheptyl (including allsubstituted isomers) and dimethylethylcycloheptyl (including allsubstituted isomers); aryl groups such as phenyl and naphthyl; alkylarylgroups such as tolyl (including all substituted isomers), xylyl(including all substituted isomers), ethylphenyl (including allsubstituted isomers), propylphenyl (including all branched isomers andsubstituted isomers), methylethylphenyl (including all substitutedisomers), trimethylphenyl (including all substituted isomers),butylphenyl (including all branched isomers and substituted isomers),methylpropylphenyl (including all branched isomers and substitutedisomers), diethylphenyl (including all substituted isomers),dimethylethylphenyl (including all substituted isomers), pentylphenyl(including all branched isomers and substituted isomers), hexylphenyl(including all branched isomers and substituted isomers), heptylphenyl(including all branched isomers and substituted isomers), octylphenyl(including all branched isomers and substituted isomers), nonylphenyl(including all branched isomers and substituted isomers), decylphenyl(including all branched isomers and substituted isomers), undecylphenyl(including all branched isomers and substituted isomers), dodecylphenyl(including all branched isomers and substituted isomers), tridecylphenyl(including all branched isomers and substituted isomers),tetradecylphenyl (including all branched isomers and substitutedisomers), pentadecylphenyl (including all branched isomers andsubstituted isomers), hexadecylphenyl (including all branched isomersand substituted isomers), heptadecylphenyl (including all branchedisomers and substituted isomers) and octadecylphenyl (including allbranched isomers and substituted isomers); and arylalkyl groups such asbenzyl, phenethyl, phenylpropyl (including all branched isomers) andphenylbutyl (including all branched isomers).

According to the invention, using at least one compound selected fromthe group consisting of dihydrocarbyl polysulfides and sulfidized estersamong the aforementioned sulfur compounds is preferred since it willallow an even higher level of machining efficiency and tool life to beachieved.

As specific examples of phosphorus compounds there may be mentionedphosphoric acid esters, acidic phosphoric acid esters, acidic phosphoricacid ester amine salts, chlorinated phosphoric acid esters, phosphorousacid esters and phosphorothionates, as well as metal salts of phosphoruscompounds represented by the following general formula (D-6) or (D-7).These phosphorus compounds may also be esters of phosphoric acid,phosphorous acid or thiophosphoric acid with alkanols or polyetheralcohols, or derivatives thereof.

[wherein Y³, Y⁴ and Y⁵ may be the same or different and each representsan oxygen or sulfur atom, with the proviso that at least two of Y³, Y⁴and Y⁵ are oxygen atoms, while R³⁴, R³⁵ and R³⁶ may be the same ordifferent and each represents hydrogen or a C1-30 hydrocarbon group.]

[wherein Y⁶, Y⁷, Y⁸ and Y⁹ may be the same or different and eachrepresents an oxygen atom or sulfur atom, with the proviso that at leastthree among Y⁶, Y⁷, Y⁸ and Y⁹ are oxygen atoms, while R³⁷, R³⁸ and R³⁹may be the same or different and each represents hydrogen or a C1-30hydrocarbon group.]

More specifically, as phosphoric acid esters there may be mentionedtributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptylphosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate,triundecyl phosphate, tridodecyl phosphate, tritridecyl phosphate,tritetradecyl phosphate, tripentadecyl phosphate, trihexadecylphosphate, triheptadecyl phosphate, trioctadecyl phosphate, trioleylphosphate, triphenyl phosphate, tricresyl phosphate, trixylenylphosphate, cresyldiphenyl phosphate, xylenyldiphenyl phosphate and thelike;

as acidic phosphoric acid esters there may be mentioned monobutyl acidphosphate, monopentyl acid phosphate, monohexyl acid phosphate,monoheptyl acid phosphate, monooctyl acid phosphate, monononyl acidphosphate, monodecyl acid phosphate, monoundecyl acid phosphate,monododecyl acid phosphate, monotridecyl acid phosphate, monotetradecylacid phosphate, monopentadecyl acid phosphate, monohexadecyl acidphosphate, monoheptadecyl acid phosphate, monooctadecyl acid phosphate,monooleyl acid phosphate, dibutyl acid phosphate, dipentyl acidphosphate, dihexyl acid phosphate, diheptyl acid phosphate, dioctyl acidphosphate, dinonyl acid phosphate, didecyl acid phosphate, diundecylacid phosphate, didodecyl acid phosphate, ditridecyl acid phosphate,ditetradecyl acid phosphate, dipentadecyl acid phosphate, dihexadecylacid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate,dioleyl acid phosphate and the like;as acidic phosphoric acid ester amine salts there may be mentioned saltsof amines such as methylamines, ethylamines, propylamines, butylamines,pentylamines, hexylamines, heptylamines, octylamines, dimethylamines,diethylamines, dipropylamines, dibutylamines, dipentylamines,dihexylamines, diheptylamines, dioctylamines, trimethylamines,triethylamines, tripropylamines, tributylamines, tripentylamines,trihexylamines, triheptylamine and trioctylamines of the aforementionedacidic phosphoric acid esters;as chlorinated phosphoric acid esters there may be mentionedtris.dichloropropyl phosphate, tris.chloroethyl phosphate,tris.chlorophenyl phosphate,polyoxyalkylene.bis[di(chloroalkyl)]phosphate and the like;as phosphorous acid esters there may be mentioned dibutyl phosphite,dipentyl phosphite, dihexyl phosphite, diheptyl phosphite, dioctylphosphite, dinonyl phosphite, didecyl phosphite, diundecyl phosphite,didodecyl phosphite, dioleyl phosphite, diphenyl phosphite, dicresylphosphite, tributyl phosphite, tripentyl phosphite, trihexyl phosphite,triheptyl phosphite, trioctyl phosphite, trinonyl phosphite, tridecylphosphite, triundecyl phosphite, tridodecyl phosphite, trioleylphosphite, triphenyl phosphite, tricresyl phosphite and the like; and asphosphorothionates there may be mentioned tributyl phosphorothionate,tripentyl phosphorothionate, trihexyl phosphorothionate, triheptylphosphorothionate, trioctyl phosphorothionate, trinonylphosphorothionate, tridecyl phosphorothionate, triundecylphosphorothionate, tridodecyl phosphorothionate, tritridecylphosphorothionate, tritetradecyl phosphorothionate, tripentadecylphosphorothionate, trihexadecyl phosphorothionate, triheptadecylphosphorothionate, trioctadecyl phosphorothionate, trioleylphosphorothionate, triphenyl phosphorothionate, tricresylphosphorothionate, trixylenyl phosphorothionate, cresyldiphenylphosphorothionate, xylenyldiphenyl phosphorothionate,tris(n-propylphenyl)phosphorothionate,tris(isopropylphenyl)phosphorothionate, tris(n-butylphenyl)phosphorothionate, tris(isobutylphenyl)phosphorothionate,tris(s-butylphenyl)phosphorothionate and tris(t-butylphenyl)phosphorothionate.

For metal salts of the phosphorus compounds represented by generalformulas (D-6) and (D-7) above, alkyl, cycloalkyl, alkenyl,alkylcycloalkyl, aryl, alkylaryl and arylalkyl groups may be mentionedas specific examples of C1-30 hydrocarbon groups represented by R³⁴-R³⁹in the formulas.

As examples of the aforementioned alkyl groups there may be mentionedalkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl,heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl,pentadecyl, hexadecyl, heptadecyl and octadecyl (where the alkyl groupsmay be straight-chain or branched).

As the aforementioned cycloalkyl groups there may be mentioned C5-7cycloalkyl groups such as cyclopentyl, cyclohexyl and cycloheptyl. Asexamples of the aforementioned alkylcycloalkyl groups there may bementioned C6-11 alkylcycloalkyl groups such as methylcyclopentyl,dimethylcyclopentyl, methylethylcyclopentyl, diethylcyclopentyl,methylcyclohexyl, dimethylcyclohexyl, methyl ethylcyclohexyl,diethylcyclohexyl, methylcycloheptyl, dimethylcycloheptyl, methylethylcycloheptyl and diethylcycloheptyl (with any positions ofsubstitution of the alkyl groups on the cycloalkyl groups).

As examples of the aforementioned alkenyl groups there may be mentionedalkenyl groups such as butenyl, pentenyl, hexenyl, heptenyl, octenyl,nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl,pentadecenyl, hexadecenyl, heptadecenyl and octadecenyl (where thealkenyl groups may be straight-chain or branched, and the double bondsmay be at any positions).

As examples of the aforementioned aryl groups there may be mentionedaryl groups such as phenyl and naphthyl. As examples of theaforementioned alkylaryl groups there may be mentioned C7-18 alkylarylgroups such as tolyl, xylyl, ethylphenyl, propylphenyl, butylphenyl,pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, nonylphenyl,decylphenyl, undecylphenyl and dodecylphenyl (where the alkyl groups maybe straight-chain or branched and substituted at any positions on thearyl groups).

As examples of the aforementioned arylalkyl groups there may bementioned C7-12 arylalkyl groups such as benzyl, phenylethyl,phenylpropyl, phenylbutyl, phenylpentyl and phenylhexyl (where the alkylgroups may be straight-chain or branched).

The C1-30 hydrocarbon groups represented by R³⁴-R³⁹ are preferably C1-30alkyl or C6-24 aryl groups, more preferably C3-18 alkyl groups and evenmore preferably C4-12 alkyl groups.

Here, R³⁴, R³⁵ and R³⁶ may be the same or different and each representshydrogen or one of the aforementioned hydrocarbon groups, wherepreferably 1-3 from among R³⁴, R³⁵ and R³⁶ are the aforementionedhydrocarbon groups, more preferably 1-2 are the aforementionedhydrocarbon groups and even more preferably two are the aforementionedhydrocarbon groups.]

Also, R³⁷, R³⁸ and R³⁹ may be the same or different and each representshydrogen or one of the aforementioned hydrocarbon groups, wherepreferably 1-3 from among R³⁷, R³⁸ and R³⁹ are the aforementionedhydrocarbon groups, more preferably 1-2 are the aforementionedhydrocarbon groups and even more preferably two are the aforementionedhydrocarbon groups.]

For the phosphorus compound represented by general formula (D-6), atleast two among Y³-Y⁵ must be oxygen atoms, but preferably all of Y³-Y⁵are oxygen atoms.

For the phosphorus compound represented by general formula (D-7), atleast two among Y⁶-Y⁹ must be oxygen atoms, but preferably all of Y⁶-Y⁹are oxygen atoms.

As examples of phosphorus compounds represented by general formula (D-6)there may be mentioned phosphorous acid and monothiophosphorous acid;phosphorous acid monoesters and monothiophosphorous acid monoesterscontaining one of the aforementioned C1-30 hydrocarbon groups,phosphorous acid diesters and monothiophosphorous acid diesterscontaining two of the aforementioned C1-30 hydrocarbon groups;phosphorous acid triesters and monothiophosphorous acid triesterscontaining three of the aforementioned C1-30 hydrocarbon groups; andmixtures thereof. Preferred among these are phosphorous acid monoestersand phosphorous acid diesters, with phosphorous acid diesters being morepreferred.

As examples of phosphorus compounds represented by general formula (D-7)there may be mentioned phosphoric acid and monothiophosphoric acid;phosphoric acid monoesters and monothiophosphoric acid monoesterscontaining one of the aforementioned C1-30 hydrocarbon groups,phosphoric acid diesters and monothiophosphoric acid diesters containingtwo of the aforementioned C1-30 hydrocarbon groups; phosphoric acidtriesters and monothiophosphoric acid triesters containing three of theaforementioned C1-30 hydrocarbon groups; and mixtures thereof. Preferredamong these are phosphoric acid monoesters and phosphoric acid diesters,with phosphoric acid diesters being more preferred.

As metal salts of phosphorus compounds represented by general formulas(D-6) and (D-7) there may be mentioned salts obtained by neutralizationof all or a portion of the acidic hydrogens of the phosphorus compoundsusing metal bases. As such metal bases there may be mentioned metaloxides, metal hydroxides, metal carbonates, metal chlorides and thelike, where specific examples of metals include alkali metals such aslithium, sodium, potassium and cesium, alkaline earth metals such ascalcium, magnesium and barium and heavy metals such as zinc, copper,iron, lead, nickel, silver, manganese and the like. Preferred amongthese are alkaline earth metals such as calcium and magnesium, and zinc.

These phosphorus compound metal salts will differ in structure dependingon the valence of the metal and the number of OH groups or SH groups inthe phosphorus compound, and therefore no limitations are placed on thestructure; however, when 1 mole of zinc oxide is reacted with 2 moles ofa phosphoric acid diester (with one OH group), for example, a compoundhaving the structure represented by formula (D-8) below may be obtainedas the major component, although polymerized molecules may also bepresent.

Also, when 1 mole of zinc oxide is reacted with 1 mole of a phosphoricacid monoester (with two OH groups), for example, a compound having thestructure represented by (D-9) below may be obtained as the majorcomponent, although polymerized molecules may also be present.

Two or more of these may also be used in admixture.

According to the invention, phosphoric acid esters, acidic phosphoricacid esters and acidic phosphoric acid ester amines are preferred amongthese phosphorus compounds from the standpoint of achieving superiormachining efficiency and tool life.

As described hereunder, the oil composition of the invention may beapplied for purposes other than metal working, and when the oilcomposition of the invention is used as an oil for machine tool slidingsurfaces, it preferably comprises an acidic phosphoric acid ester or anacidic phosphoric acid ester amine salt. Also, when the oil compositionof the invention is used as a hydraulic oil, a phosphoric acid ester ispreferred. When it is used as both a sliding surface oil and a hydraulicoil, it is preferred to use a combination of a phosphoric acid esterwith at least one selected from among acidic phosphoric acid esters andacidic phosphoric acid ester amine salts.

The oil composition of the invention may contain either a sulfurcompound or phosphorus compound, or it may contain both. From thestandpoint of achieving superior machining efficiency and tool life, itpreferably contains a phosphorus compound or both a sulfur compound andphosphorus compound, and more preferably it contains both a sulfurcompound and phosphorus compound.

The content of the (D) extreme pressure agent may be as desired, butfrom the standpoint of achieving superior machining efficiency and toollife, it is preferably at least 0.005% by mass, more preferably at least0.01% by mass and even more preferably at least 0.05% by mass, based onthe total weight of the composition. From the viewpoint of preventingabnormal abrasion, the extreme pressure agent content is preferably nogreater than 20% by mass, more preferably no greater than 15% by massand even more preferably no greater than 12% by mass, based on the totalweight of the composition.

According to the invention, the aforementioned (C) oil agent or (D)extreme pressure agent may be used alone, but from the viewpoint ofachieving superior machining efficiency and tool life, the (C) oil agentand (D) extreme pressure agent are preferably used in combination.

The oil composition of the invention preferably also further contains(E) an organic acid salt, from the viewpoint of achieving superiormachining efficiency and tool life. As organic acid salts there arepreferably used sulfonates, phenates, salicylates and mixtures thereof.As cationic components for these organic acid salts there may bementioned alkali metals such as sodium and potassium; alkaline earthmetals such as magnesium, calcium and barium; ammonia, amines such asC1-3 alkyl group-containing alkylamines (monomethylamine, dimethylamine,trimethylamine, monoethylamine, diethylamine, triethylamine,monopropylamine, dipropylamine, tripropylamine and the like), C1-3alkanol group-containing alkanolamines (monomethanolamine,dimethanolamine, trimethanolamine, monoethanolamine, diethanolamine,triethanolamine, monopropanolamine, dipropanolamine, tripropanolamineand the like), and zinc, but alkali metals and alkaline earth metals arepreferred among these, and calcium is particularly preferred. Using analkali metal or alkaline earth metal as the cationic component of theorganic acid salt will tend to produce even higher lubricity.

The sulfonate used may be one produced by any desired process. Forexample, there may be used alkali metal salts, alkaline earth metalsalts and amine salts of alkylaromatic sulfonic acids obtained bysulfonation of alkylaromatic compounds with molecular weights of100-1500 and preferably 200-700, as well as mixtures thereof. As thealkylaromatic sulfonic acids referred to here there may be mentionedsynthetic sulfonic acids including sulfonated alkylaromatic compounds oflube-oil distillates of common mineral oils, petroleum sulfonic acidssuch as “mahogany acid” yielded as a by-product of white oil production,sulfonated products of alkylbenzenes with straight-chain or branchedalkyl groups, which are by-products in production plants foralkylbenzenes used as starting materials for detergents or are obtainedby alkylation of benzene with polyolefins, and sulfonatedalkylnaphthalenes such as dinonylnaphthalene. There may also bementioned neutral (normal) sulfonates obtained by reacting theaforementioned alkylaromatic sulfonic acids with alkali metal bases(alkali metal oxides, hydroxides and the like), alkaline earth metalbases (alkaline earth metal oxides, hydroxides and the like) or theaforementioned amines (ammonia, alkylamines, alkanolamines, etc.); basicsulfonates obtained by heating neutral (normal) sulfonates with anexcess of an alkali metal base, alkaline earth metal base or amine inthe presence of water; “carbonated overbased sulfonates” obtained byreacting neutral (normal) sulfonates with alkali metal bases, alkalineearth metal bases or amines in the presence of carbon dioxide gas;“borated overbased sulfonates” produced by reacting neutral (normal)sulfonates with alkali metal bases, alkaline earth metal bases or aminesand boric acid compounds such as boric acid and boric anhydride, or byreacting carbonated overbased sulfonates with boric acid compounds suchas boric acid and boric anhydride; as well as mixtures of theabove-mentioned compounds.

As phenates there may be mentioned, specifically, neutral phenatesobtained by reacting alkylphenols having one or two C4-20 alkyl groupswith alkali metal bases (alkali metal oxides, hydroxides and the like),alkaline earth metal bases (alkaline earth metal oxides, hydroxides andthe like) or the aforementioned amines (ammonia, alkylamines,alkanolamines, etc.) in the presence or in the absence of elementalsulfur; basic phenates obtained by heating neutral phenates with anexcess of an alkali metal base, alkaline earth metal base or amine inthe presence of water; “carbonated overbased phenates” obtained byreacting neutral phenates with alkali metal bases, alkaline earth metalbases or amines in the presence of carbon dioxide gas; “boratedoverbased phenates” produced by reacting neutral phenates with alkalimetal bases, alkaline earth metal bases or amines and boric acidcompounds such as boric acid and boric anhydride, or by reactingcarbonated overbased phenates with boric acid compounds such as boricacid and boric anhydride; as well as mixtures of the above-mentionedcompounds.

As salicylates there may be mentioned, specifically, neutral salicylatesobtained by reacting alkylsalicylic acids having one or two C4-20 alkylgroups with alkali metal bases (alkali metal oxides, hydroxides and thelike), alkaline earth metal bases (alkaline earth metal oxides,hydroxides and the like) or the aforementioned amines (ammonia,alkylamines, alkanolamines, etc.) in the presence or in the absence ofelemental sulfur; basic salicylates obtained by heating neutralsalicylates with an excess of an alkali metal base, alkaline earth metalbase or amine in the presence of water; “carbonated overbasedsalicylates” obtained by reacting neutral salicylates with alkali metalbases, alkaline earth metal bases or amines in the presence of carbondioxide gas; “borated overbased salicylates” produced by reactingneutral salicylates with alkali metal bases, alkaline earth metal basesor amines and boric acid compounds such as boric acid and boricanhydride, or by reacting carbonated overbased salicylates with boricacid compounds such as boric acid and boric anhydride; as well asmixtures of the above-mentioned compounds.

The base value of the (E) organic acid salt is preferably 50-500 mgKOH/gand more preferably 100-450 mgKOH/g. If the total base value of theorganic acid salt is less than 100 mgKOH/g the lubricity-enhancingeffect of the organic acid salt addition will tend to be unsatisfactory,while organic acid salts with a total base value of greater than 500mgKOH/g are also not preferred because they are generally very difficultto produce and obtain. The base value referred to here is the base value[mgKOH/g] measured by a perchloric acid method based on section 7 of“Petroleum product and lubricating oils—Neutralization value testmethods” of JIS K 2501.

The content of the (E) organic acid salt is preferably 0.1-30% by mass,more preferably 0.5-25% by mass and even more preferably 1-20% by massbased on the total weight of the composition. If the content of the (E)organic acid salt is below this lower limit, the improving effect of theaddition on the machining efficiency and tool life will tend to beunsatisfactory, while if it is above the aforementioned upper limit thestability of the oil composition will be reduced and deposits will tendto form.

According to the invention, the (E) organic acid salt may be used aloneor the organic acid salt may be used in combination with otheradditives. From the standpoint of achieving superior machiningefficiency and tool life, it is preferred to use a combination of anorganic acid salt with the aforementioned extreme-pressure agent, and itis particularly preferred to use a combination of three components, asulfur compound, a phosphorus compound and an organic acid salt.

The oil composition of the invention preferably further contains (F) anantioxidant. Addition of an antioxidant can prevent sticking caused bydegradation of the constituent components, while further enhancing theheat and oxidation stability.

As (F) antioxidants there may be mentioned phenol-based antioxidants,amine-based antioxidants, zinc dithiophosphate-based antioxidants, andantioxidants used as food additives.

As phenol-based antioxidants there may be used any phenol-basedcompounds that are employed as antioxidants for lubricating oils, withno particular restrictions, and as preferred examples there may bementioned one or more alkylphenol compounds selected from amongcompounds represented by the following general formulas (F-1) and (F-2).

[wherein R⁴⁰ represents a C1-4 alkyl group, R⁴¹ represents hydrogen or aC1-4 alkyl group, and R⁴² represents hydrogen, a C1-4 alkyl group, or agroup represented by the following general formula (i) or (ii):

(where R⁴³ represents C1-6 alkylene and R⁴⁴ represents a C1-24 alkyl oralkenyl group)

(where R⁴⁵ represents a C1-6 alkylene group, R⁴⁶ represents a C1-4 alkylgroup, R⁴⁷ represents hydrogen or a C1-4 alkyl group and k represents 0or 1).]

[wherein R⁴⁸ and R⁵⁰ may be the same or different and each representsC1-4 alkyl, R⁴⁹ and R⁵¹ may be the same or different and each representshydrogen or C1-4 alkyl, R⁵² and R⁵³ may be the same or different andeach represents C1-6 alkylene, and B represents C1-18 alkylene or agroup represented by the following general formula (iii):

—R⁵⁵—S—R⁵⁶—  (iii)

(where R⁵⁵ and R⁵⁶ may be the same or different and each represents aC1-6 alkylene group).]

As amine-based antioxidants for the invention there may be used anyamine-based compounds that are employed as antioxidants for lubricatingoils, with no particular restrictions, and as preferred examples theremay be mentioned one or more aromatic amines selected from amongphenyl-α-naphthylamine or N-p-alkylphenyl-α-naphthylamines representedby the following general formula (F-3), and p,p′-dialkyldiphenylaminesrepresented by the following general formula (F-4).

[wherein R⁵⁷ represents hydrogen or an alkyl group.]

[wherein R⁵⁸ and R⁵⁹ may be the same or different and each represents analkyl group.]

As specific examples of amine-based antioxidants there may be mentioned4-butyl-4′-octyldiphenylamine, phenyl-α-naphthylamine,octylphenyl-α-naphthylamine, dodecylphenyl-α-naphthylamine, and mixturesthereof.

As dithiozinc phosphate-based antioxidants there may be mentioned zincdithiophosphate compounds represented by general formula (D-2) above.

Antioxidants employed as food additives may also be used, although thesepartially overlap with the aforementioned phenol-based antioxidants, andthere may be mentioned as examples 2,6-di-tert-butyl-p-cresol (DBPC),4,4′-methylenebis(2,6-di-tert-butylphenol),4,4′-bis(2,6-di-tert-butylphenol), 4,4′-thiobis(6-tert-butyl-o-cresol),ascorbic acid (vitamin C), ascorbic acid fatty acid esters, tocopherol(vitamin E), 3,5-di-tert-butyl-4-hydroxyanisole,2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole,1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline (ethoxyquin),2-(1,1-dimethyl)-1,4-benzenediol (TBHQ) and2,4,5-trihydroxybutyrophenone (THBP).

Preferred among these antioxidants are phenol-based antioxidants,amine-based antioxidants and antioxidants that are employed as foodadditives. The use of food additive antioxidants is especially preferredwhen biodegradability is a primary concern, and of these, ascorbic acid(vitamin C), ascorbic acid fatty acid esters, tocopherol (vitamin E),2,6-di-tert-butyl-p-cresol (DBPC), 3,5-di-tert-butyl-4-hydroxyanisole,2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole,1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline (ethoxyquin),2-(1,1-dimethyl)-1,4-benzenediol (TBHQ) and2,4,5-trihydroxybutyrophenone (THBP) are preferred, among which ascorbicacid (vitamin C), ascorbic acid fatty acid esters, tocopherol (vitaminE), 2,6-di-tert-butyl-p-cresol (DBPC) and3,5-di-tert-butyl-4-hydroxyanisole are more preferred.

There are no particular restrictions on the (F) antioxidant content, butfor maintenance of satisfactory heat and oxidation stability the contentis preferably 0.01% by mass or greater, more preferably 0.05% by mass orgreater and most preferably 0.1% by mass or greater based on the totalweight of the composition. Since no corresponding effect can be expectedwith larger amounts of addition, the content is preferably no greaterthan 10% by mass, more preferably no greater than 5% by mass and mostpreferably no greater than 3% by mass.

The oil composition of the invention may contain various additives knownin the prior art in addition to those mentioned above. As examples ofsuch additives there may be mentioned extreme pressure agents (includingchlorine-based extreme pressure agents) other than the aforementionedphosphorus compounds and sulfur compounds; moistening agents such asdiethyleneglycol monoalkylethers; film-forming agents such as acrylicpolymers, paraffin wax, microwax, slack wax and polyolefin wax; waterdisplacement agents such as fatty acid amine salts; solid lubricantssuch as graphite, fluorinated graphite, molybdenum disulfide, boronnitride and polyethylene powder; corrosion inhibitors such as amines,alkanolamines, amides, carboxylic acids, carboxylic acid salts, sulfonicacid salts, phosphoric acid, phosphoric acid salts and polyhydricalcohol partial esters; metal inactivators such as benzotriazole andthiadiazole; antifoaming agents such as methylsilicone, fluorosiliconeand polyacrylate; and non-ash dispersants such as alkenylsuccinicimides, benzylamine and polyalkenylamineaminoamides. The contents ofsuch known additives when used in combination are not particularlyrestricted, but they are generally added in amounts so that the totalcontent of the known additives is 0.1-10% by mass based on the totalweight of the composition.

The oil composition of the invention may also contain chlorine-basedadditives such as the aforementioned chlorine-based extreme-pressureagents, but they preferably contain no chlorine-based additives from theviewpoint of improving stability and reducing the burden on theenvironment. The chlorine concentration is preferably no greater than1000 ppm by mass, more preferably no greater than 500 ppm by mass, evenmore preferably no greater than 200 ppm by mass and most preferably nogreater than 100 ppm by mass, based on the total weight of thecomposition.

There are no particular restrictions on the kinematic viscosity of theoil composition of the invention, but from the standpoint offacilitating supply to the working section, the kinematic viscosity at100° C. is preferably no greater than 20 mm²/s, more preferably nogreater than 17 mm²/s, even more preferably no greater than 15 mm²/s andmost preferably no greater than 12 mm²/s. On the other hand, thekinematic viscosity of the oil composition of the invention at 100° C.is preferably at least 0.5 mm²/s, more preferably at least 0.7 mm²/s andmost preferably at least 0.9 mm²/s.

From the standpoint of storage stability and rust prevention, themoisture content of the oil composition of the invention is preferablyno greater than 20,000 ppm, more preferably no greater than 10,000 ppmand even more preferably no greater than 5000 ppm. From the viewpoint ofachieving superior machining efficiency and tool life, the moisturecontent is preferably at least 200 ppm, more preferably at least 300ppm, even more preferably at least 400 ppm and yet more preferably atleast 500 ppm.

The moisture content according to the invention is the moisture contentas measured by Karl Fischer coulometric titration based on JIS K 2275.

When the moisture content of the oil composition of the invention isadjusted by addition of water, the added water may be hard water or softwater, and the source of water used may be tap water, industrial water,ion-exchanged water, distilled water, alkali ion water or the like.

The oil composition of the invention having the construction describedabove can achieve both misting and floating mist properties that havebeen difficult to achieve by the prior art with cutting and grinding inminimum quantity lubrication systems. The oil composition of theinvention is therefore highly useful for enhancing machining performanceand improving working environments.

EXAMPLES

The present invention will now be explained in greater detail based onexamples and comparative examples, with the understanding that theseexamples are in no way limitative on the invention.

Examples 1-14 Comparative Example 1

For Examples 1-14 and Comparative Example 1, the ester oils andester-based polymers listed below were used to prepare the oilcompositions shown in Tables 1 to 3.

(Ester Oils)

A1: Methyl oleate (kinematic viscosity at 100° C.: 1.8 mm²/s)A2: Diisodecyl adipate (kinematic viscosity at 100° C.: 3.7 mm²/s)A3: Triester of trimethylolpropane and n-octanoic acid/n-decanoic acidmixed acid (kinematic viscosity at 100° C.: 4.4 mm²/s)A4: Diester of neopentyl glycol and oleic acid (kinematic viscosity at100° C.: 5.8 mm²/s)A5: High-oleic rapeseed oil (kinematic viscosity at 100° C.: 8.5 mm²/s)A6: Triester of trimethylolpropane and oleic acid (kinematic viscosityat 100° C.: 9.8 mm²/s)

(Ester-Based Polymers)

B1: Polymethacrylate (polymer comprising monomer mixture represented bygeneral formula (B-2-2) wherein R¹ is hydrogen, R² is methyl, R³ isC1-18 alkyl; kinematic viscosity at 100° C.: 400 mm²/s, averagemolecular weight: 10,000)B2: Polymethacrylate (polymer comprising monomer mixture represented bygeneral formula (B-2-2) wherein R¹ is hydrogen, R² is methyl, R³ isC1-18 alkyl; kinematic viscosity at 100° C.: 1200 mm²/s, averagemolecular weight: 50,000)B3: Polymethacrylate (polymer comprising monomer mixture represented bygeneral formula (B-2-2) wherein R¹ is hydrogen, R² is methyl, R³ isC1-18 alkyl; kinematic viscosity at 100° C.: 1700 mm²/s, averagemolecular weight: 150,000)B4: Polymethacrylate (polymer comprising monomer mixture represented bygeneral formula (B-2-2) wherein R¹ is hydrogen, R² is methyl, R³ isC1-18 alkyl; kinematic viscosity at 100° C.: 2,500 mm²/s, averagemolecular weight: 500,000)B5: Complex ester of neopentyl glycol and dimer acid (kinematicviscosity at 100° C.: 2,000 mm²/s, average molecular weight: 100,000)

The oil compositions of Examples 1-14 and Comparative Example 1 werethen subjected to the following tests.

[Floating Mist Measurement Test]

FIG. 1 and FIG. 2 are, respectively, a side view and top view of theessential parts of a test apparatus used for the floating mistmeasurement test. The test apparatus shown in FIG. 1 and FIG. 2 has anMQL device (EB-3, product of Fuji BC Engineering Co., Ltd.) and a mistcounter installed on a machining center (MB-46V, product of OkumaMachine Tools, Inc.), for cutting and grinding in minimum quantitylubrication system. Specifically, the test apparatus shown in FIG. 1 andFIG. 2 is equipped with a table 1 supporting a workpiece 10, a tool 2situated opposite the top of the table 1 (NACHI straight drill SGOH3D(5.0 mm×82 mm×28 mm), hereinafter referred to as “drill 2”), a shank 3supported in a rotatable manner around its rotation axis as the center,and a mist counter 5 (P-5L Portable Dust Monitor, product of SibataScientific Technology, Ltd.) situated around the edge of the top of thetable 1.

While not shown in detail here, the drill 2 has a helical groove, andtwo discharge holes (oil holes, φ1.0 mm) are provided at prescribedlocations on the cutting blade flank of the groove. Inside the drill 2and shank 3 there are provided channels connecting with the dischargeholes of the drill 2, and an oil feed line 5 is connected to the openingat the side of the channel of the shank 3 opposite the drill 2 side.Thus, the oil composition fed from the oil feed line 5 together withcompressed air can be converted to a mist from the discharge holes ofthe drill 2, through the channels formed by the drill 2 and shank 3,toward the workpiece 10.

In the test apparatus having this construction, cutting and grinding wasperformed with minimum quantity lubrication system at a drill rotationrate of 1,000 rpm, a misting pressure difference of 0.12 MPa (injectionpressure: 0.38 MPa, discharge pressure: 0.26 MPa), a discharge pressurefrom the misting apparatus of 0.26 MPa and blowing toward the workpieceat 180 shots/min. The amount of floating mist produced during oneminute, from 3 minutes to 4 minutes after the start of machining, wasmeasured using the mist counter 5. The results are shown in Tables 1 to3.

[Test for Measurement of Amount of Tapped Oil Reaching Cutting Point]

A glass dish (inner diameter: 95 mm) was placed in the test apparatusshown in FIG. 1 and FIG. 2 instead of the workpiece 10, and the drill 2and shank 3 were situated so that the distance between the bottom of thedish and the tip of the drill 2 was 50 mm. The misted oil compositionwas blown in from the discharge hole of the drill 2 toward the dishunder the same conditions as for the floating mist measurement test, andthe amount of oil composition collected in the dish (amount deliveredper unit time) was measured. The results are shown in Tables 1 to 3.

[Lubricity Performance Test (Tapping Test)]

Each oil composition was subjected to a tapping test under the followingconditions. Supply of the oil composition to the working section wasaccomplished by using an MQL apparatus (MCA by TACO) for blowing towardthe working section at 2 cm²/min, with a misting pressure difference of0.20 MPa (injection pressure: 0.42 MPa, discharge pressure: 0.22 MPa)and a discharge pressure of 0.22 MPa from the misting apparatus. Thetest was carried out 9 times for each oil composition, and the averagevalue for the tapping energy was calculated. The results are shown inTables 1 to 3.

(Tapping Conditions)

Tool: Nut tap M8 (P=1.25 mm)

Lower hole diameter: φ6.8 mmWorkpiece: S25C (t=10 mm)Cutting speed: 9.0 m/min

TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Composition A1 99.00 — — — — — [% by mass] A2 — 99.00 — — — — A3 — —99.00 — — — A4 — — — 99.00 — — A5 — — — — 99.00 — A6 — — — — — 99.00 B21.00 1.00 1.00 1.00 1.00 1.00 Floating mist 2.01 0.95 1.09 0.89 0.810.77 [mg/m³] Amount of tapped 7.01 8.12 7.22 7.98 7.11 6.99 oil reachingcutting point [g/h] Tapping energy 368 360 358 350 362 347 (mean) [N ·m]

TABLE 2 Example 7 Example 8 Example 9 Example 10 Example 11 CompositionA4 99.99 99.90 95.00 90.00 99.00 [% by mass] B1 — — — 10.00 1.00 B2 —0.10 5.00 — — B3 — — — — — B4 0.01 — — — — B5 — — — — — Floating mist2.07 1.88 0.77 0.69 1.18 [mg/m³] Amount of tapped 7.88 8.11 6.99 6.897.71 oil reaching cutting point [g/h] Tapping energy 362 367 360 368 361(mean) [N · m]

TABLE 3 Example Example Example Comp. 12 13 14 Ex. 1 Composition A499.00 99.00 95.00 100.00 [% by mass] B3 1.00 — — — B4 — 1.00 — — B5 — —1.00 — Floating mist 0.78 0.74 1.78 19.1 [mg/m³] Amount of tapped oil8.43 7.05 7.51 5.81 reaching cutting point [g/h] Tapping energy (mean)355 361 365 379 [N · m]

1. (canceled)
 2. A process comprising the steps of: cutting and grindinga workpiece by minimum quantity lubrication system with an oilcomposition; wherein the oil composition comprises: an ester of apolyhydric alcohol and a monobasic acid with a kinematic viscosity of0.2-12 mm²/s at 100° C., and an ester-based polymer with a kinematicviscosity exceeding 20 mm²/s to 2,500 mm²/s at 100° C. and an averagemolecular weight of 10,000-300,000; wherein the content of the ester is90.00 to 99.99% by mass and the content of the ester-based polymer is0.01 to 10.00% by mass based on a total amount of the composition.
 3. Aminimum quantity lubrication system, comprising: a cutting and grindingapparatus cutting and grinding a workpiece; a lubrication apparatusproviding a lubricant oil composition to the cutting and grindingapparatus; wherein the lubricant oil composition comprises: an ester ofa polyhydric alcohol and a monobasic acid with a kinematic viscosity of0.2-12 mm²/s at 100° C., and an ester-based polymer with a kinematicviscosity exceeding 20 mm²/s to 2,500 mm²/s at 100° C. and an averagemolecular weight of 10,000-300,000; wherein the content of the ester is90.00 to 99.99% by mass and the content of the ester-based polymer is0.01 to 10.00% by mass based on a total amount of the composition.